Fix three breaks the removals left behind

**`snapshot_revision` was deleted with `create_titled`** (bc22f8e). I sliced the
function out by scanning to the next `pub fn`, and the private `fn` sitting
between them went too. Nothing in Python or TypeScript compiles Rust, so it sat
undetected until the first lane that does. Restored verbatim.

**An orphaned serde attribute** in push.rs: removing `pub kind: Option<String>`
left its `#[serde(skip_serializing_if)]` behind, which then stacked onto the
next field's. That failed the derive, which is why three follow-on errors all
said `Change: Serialize is not satisfied` — one cause, four messages.

**An unbalanced `</div>`** in NoteEditor.vue, orphaned when the "Links / Linked
from" footer was cut. `vue-tsc --noEmit` type-checks the SCRIPT block and never
parses the template, so the typecheck lane passed it and `vite build` caught it
two workflows later. Worth remembering: a green typecheck says nothing about
template structure.

I also pushed step 2 without waiting for ad21eac to go terminal, which is what
let the Rust break travel a commit further than it should have.

Each fix comes with the check that would have caught it: a scan for stacked
serde attributes and called-but-undefined fns across every .rs, and a tag
balance pass over every .vue. Both are clean.

core/src/local/store.rs

@@ -373,6 +373,19 @@ pub fn create_note(conn: &Connection, input: &NoteCreateInput) -> rusqlite::Resu
     load_note(conn, &id)
 }
 
+fn snapshot_revision(conn: &Connection, id: &str) -> rusqlite::Result<()> {
+    let (title, body): (Option<String>, String) =
+        conn.query_row("SELECT title, body FROM notes WHERE id = ?1", [id], |r| {
+            Ok((r.get(0)?, r.get(1)?))
+        })?;
+    conn.execute(
+        "INSERT INTO note_revisions (id, note_id, title, body, created_at) VALUES (?1, ?2, ?3, ?4, ?5)",
+        params![new_id(), id, title, body, now()],
+    )?;
+    Ok(())
+}
+
+/// PATCH semantics: apply exactly the fields present in `changes`.
 pub fn update_note(conn: &Connection, id: &str, changes: &Value) -> rusqlite::Result<Note> {
     let obj = changes
         .as_object()

core/src/sync/push.rs

@@ -69,7 +69,6 @@ pub struct Change {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub color: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
-    #[serde(skip_serializing_if = "Option::is_none")]
     pub pinned: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub archived: Option<bool>,

frontend/src/components/NoteEditor.vue

@@ -627,7 +627,6 @@ function revPreview(rev: NoteRevision): string {
           </button>
         </div>
 
-          </div>
         </div>
 
         <div
@@ -750,6 +749,5 @@ function revPreview(rev: NoteRevision): string {
         </div>
       </div>
     </div>
-    </div>
   </Transition>
 </template>