Remove the title field — a note is named by its first line

Operator (note 2897): "notes shouldn't have a title field." The concept of a NAME
stays — search results, export filenames and the command palette all need one —
but nothing is typed into it any more. `display_title` is now the first non-empty
line of the body, falling back to the first checklist item.

That fallback is what step 2 bought, and the reason this could not go first: a
checklist had no body to be named from, so the title was its only name. Now every
note has a body, and a note that is only a checklist is named by its first item.

Gone everywhere: the column and note_revisions.title (0026), the field on the
core's Note/NoteCreateInput/NoteRevision and its SQLite columns (user_version 7),
`normalize_title`, the wire field, the FFI record and `NoteEdit::Title` /
`ClearTitle`, the web editor's "Title (optional)" input and the card's <h3>, and
the Android title field in both the compose sheet and the editor.

**The search vector had to be rebuilt, not just left alone.** `notes.search_vector`
is a STORED GENERATED column whose expression names `title` — Postgres refuses to
drop a column another generated column depends on. It is dropped and recreated over
`display_title` at weight A, which keeps the original intent: a note's NAME ranks
above the rest of its body.

**An imported title becomes the note's first body line.** Keep notes carry one, and
so does any ThoughtSync export taken before this. Dropping it would silently lose
text someone wrote; folding it in puts it exactly where a name now lives, so the
note arrives named as it was. Skipped when the body already opens with that line,
so re-importing an export this code produced doesn't stack duplicates.

Two smaller things fell out. The Android editor loses its bold first field — one
weight throughout, because the first line is the note's name but not a different
KIND of text, which is most of step 4 arriving early. And `ClearTitle`'s
justification comment moved to `ClearRemindAt`, which is now the surviving example
of why NoteEdit is a list rather than a struct of options.

Protocol note corrected to say what actually shipped: v2 is "no kind, no title",
one bump for the pair.

Verified with the local Rust gate this time, not by CI: fmt, clippy and 116 tests
all green before pushing. It caught four things — orphaned serde attributes where
fields were removed, a `wire::Preview.title` I deleted by mistake (a link preview
still has one), nine retention fixtures inserting a dropped column, and four
rustfmt diffs.

android/ffi/src/lib.rs

@@ -568,9 +568,8 @@ mod tests {
         dir.to_string_lossy().into_owned()
     }
 
-    fn draft(title: &str, body: &str) -> NoteDraft {
+    fn draft(body: &str) -> NoteDraft {
         NoteDraft {
-            title: title.to_string(),
             body: body.to_string(),
             color: "default".to_string(),
             items: None,
@@ -587,62 +586,50 @@ mod tests {
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
 
         let created = app
-            .create_note(draft("Groceries", "milk"))
+            .create_note(draft("Groceries\nmilk"))
             .expect("create should succeed");
-        assert_eq!(created.title.as_deref(), Some("Groceries"));
-        assert_eq!(created.body, "milk");
+        assert_eq!(created.body, "Groceries\nmilk");
 
         let fetched = app
             .get_note(created.id.clone())
             .expect("get should succeed");
         assert_eq!(fetched.id, created.id);
+        // The NAME is the first line — there is no title field to have set (M13 step 3).
         assert_eq!(fetched.display_title, "Groceries");
 
         std::fs::remove_dir_all(&dir).ok();
     }
 
-    /// A body-only note still has to be nameable — that is what `display_title` is
-    /// for, and the Android board relies on it exactly as the desktop does.
+    /// Every note has to be nameable — that is what `display_title` is for, and the
+    /// Android board relies on it exactly as the desktop does.
     #[test]
-    fn body_only_notes_still_have_a_display_title() {
+    fn a_note_is_named_by_its_first_line() {
         let dir = scratch_dir();
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
 
         let created = app
-            .create_note(draft("", "just a thought"))
+            .create_note(draft("just a thought"))
             .expect("create should succeed");
-        assert_eq!(created.title, None);
         assert_eq!(created.display_title, "just a thought");
 
         std::fs::remove_dir_all(&dir).ok();
     }
 
-    /// Clearing a field and setting one are different edits, and the difference has
-    /// to survive the trip through the patch object.
+    /// The hole that made removing the title unsafe until checklists stopped being
+    /// their own kind of thing: a note with no body text still needs a name.
     #[test]
-    fn edits_can_both_set_and_clear_a_title() {
+    fn a_note_with_only_items_is_named_by_its_first_item() {
         let dir = scratch_dir();
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
-        let note = app.create_note(draft("First", "body")).expect("create");
 
-        let renamed = app
-            .update_note(
-                note.id.clone(),
-                vec![NoteEdit::Title {
-                    value: "Second".to_string(),
-                }],
-            )
-            .expect("rename");
-        assert_eq!(renamed.title.as_deref(), Some("Second"));
-
-        let cleared = app
-            .update_note(note.id.clone(), vec![NoteEdit::ClearTitle])
-            .expect("clear");
-        assert_eq!(
-            cleared.title, None,
-            "ClearTitle must null the column, not set it to an empty string — the \
-             distinction is why NoteEdit is a list rather than a struct of options"
-        );
+        let created = app
+            .create_note(NoteDraft {
+                body: String::new(),
+                color: "default".to_string(),
+                items: Some(vec!["milk".to_string(), "eggs".to_string()]),
+            })
+            .expect("create should succeed");
+        assert_eq!(created.display_title, "milk");
 
         std::fs::remove_dir_all(&dir).ok();
     }
@@ -673,8 +660,7 @@ mod tests {
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
         let note = app
             .create_note(NoteDraft {
-                title: "Packing".to_string(),
-                body: String::new(),
+                body: "Packing".to_string(),
                 color: "default".to_string(),
                 items: Some(vec!["socks".to_string()]),
             })
@@ -728,7 +714,7 @@ mod tests {
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
 
         let note = app
-            .create_note(draft("Trip", "book the ferry #travel"))
+            .create_note(draft("Trip\nbook the ferry #travel"))
             .expect("create");
         assert_eq!(
             note.labels.len(),
@@ -767,7 +753,7 @@ mod tests {
     fn deleting_forever_removes_the_note() {
         let dir = scratch_dir();
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
-        let note = app.create_note(draft("Ephemeral", "body")).expect("create");
+        let note = app.create_note(draft("Ephemeral\nbody")).expect("create");
 
         app.delete_note_forever(note.id.clone())
             .expect("delete forever");
@@ -784,7 +770,7 @@ mod tests {
     fn reminders_can_be_snoozed_and_completed() {
         let dir = scratch_dir();
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
-        let note = app.create_note(draft("Call back", "")).expect("create");
+        let note = app.create_note(draft("Call back")).expect("create");
         assert_eq!(note.remind_at, None);
 
         let snoozed = app.snooze_reminder(note.id.clone(), 60).expect("snooze");
@@ -810,9 +796,7 @@ mod tests {
     fn completing_a_recurring_reminder_moves_it_rather_than_ending_it() {
         let dir = scratch_dir();
         let app = ThoughtSync::new(dir.clone()).expect("a fresh data dir should open");
-        let note = app
-            .create_note(draft("Water the plants", ""))
-            .expect("create");
+        let note = app.create_note(draft("Water the plants")).expect("create");
 
         let armed = app
             .update_note(
@@ -849,9 +833,7 @@ mod tests {
 
         // A one-off clears BOTH fields, so an unrecognised rule cannot linger
         // invisibly on a note with no reminder.
-        let once = app
-            .create_note(draft("Post the letter", ""))
-            .expect("create");
+        let once = app.create_note(draft("Post the letter")).expect("create");
         app.update_note(
             once.id.clone(),
             vec![NoteEdit::RemindAt {