A checklist is something a note has, not something a note is

`kind` was never a type. A plain TEXT column with no enum and no CHECK behind
it, compared against a hardcoded ("text", "list") tuple in six places;
`note_items` was always an ordinary child table keyed by note_id; serialization
already emitted `items` whatever the kind; and the Android editor already
toggled between the two losslessly, saying so in a comment. The storage has
modelled "a body plus optional checkable items" the whole time. This deletes the
gates that forbade it.

Every surface: the create/PATCH gates, the ?kind= filter and its saved-filter
facet, the three import/export branches, the column (alembic 0025); the core's
`kind` field, its SQLite column (user_version 6), the sync wire, push and pull;
the FFI records and `NoteEdit::Kind`; and on Android `NoteKind.kt`, `DraftKind`,
the compose sheet's Note/List switch, and the branches in the card, the editor
and the chrome.

The editor's note⇄list toggle becomes "Add a checklist" — on both the web and
Android. It is not a conversion any more: nothing moves, nothing is swapped, the
body stays exactly where it is and the note gains somewhere to put items. The
card renders both, in order.

Two things that fell out of the merge rather than being aimed at:

- The Keep importer was DISCARDING `textContent` whenever a note also had
  `listContent`, because the target could only hold one. Both survive now, and
  the test says so.
- Markdown export wrote the body OR the checklist. It writes both.

Protocol goes to v2, floor included: dropping a field a v1 client sends and
expects back is breaking. `title` leaves in step 3 and lands in the same
generation, so it needs no further bump. This is the change that will make the
0.1.227 build on the operator's phone refuse to sync — the in-app updater is
independent of the handshake and remains the recovery path.

The V1 SQLite schema deliberately KEEPS the kind column. V1 is the historical
schema and every later block alters it, so removing it there would make a fresh
database run V1 without the column and then v6's DROP COLUMN against a column
that never existed — "no such column: kind" on every new install.

src/thoughtsync/notes/__init__.py

@@ -101,7 +101,6 @@ async def list_notes():
     # saved-filter lens. Multiple ?label= narrow to notes carrying ALL of them.
     label_params = request.args.getlist("label")
     color = request.args.get("color")
-    kind = request.args.get("kind")
     has_reminder = coerce_bool(request.args.get("has_reminder"))
     has_attachment = coerce_bool(request.args.get("has_attachment"))
     query_text = (request.args.get("q") or "").strip()
@@ -125,10 +124,6 @@ async def list_notes():
             if color not in NOTE_COLORS:
                 return json_error("invalid color", 400)
             stmt = stmt.where(Note.color == color)
-        if kind is not None:
-            if kind not in ("text", "list"):
-                return json_error("invalid kind", 400)
-            stmt = stmt.where(Note.kind == kind)
         if has_reminder:
             stmt = stmt.where(Note.remind_at.is_not(None))
         if has_attachment:
@@ -282,7 +277,6 @@ async def export_notes():
                         "display_title": n.display_title,
                         "body": n.body,
                         "color": n.color,
-                        "kind": n.kind,
                         "pinned": n.pinned,
                         "archived": n.archived,
                         "remind_at": n.remind_at.isoformat() if n.remind_at else None,
@@ -418,14 +412,11 @@ async def create_note():
     data = await request.get_json(silent=True) or {}
     title = data.get("title") if isinstance(data.get("title"), str) else ""
     body = data.get("body") if isinstance(data.get("body"), str) else ""
-    kind = data.get("kind") if data.get("kind") in ("text", "list") else "text"
-    # A checklist note's "content" is its items, not the body — so it's non-empty
-    # when it has a title or at least one item (quick-add can create one in one shot).
-    item_texts = parse_list_items(data.get("items")) if kind == "list" else []
-    if kind == "list":
-        if not (title.strip() or item_texts):
-            return json_error("note is empty", 400)
-    elif is_empty_note(title, body):
+    # Items are accepted on ANY note now — a checklist is something a note HAS.
+    item_texts = parse_list_items(data.get("items"))
+    # "Empty" therefore means all three are empty, not just the two that used to
+    # matter for whichever kind this was.
+    if is_empty_note(title, body) and not item_texts:
         return json_error("note is empty", 400)
     async with session_scope() as db:
         # New notes go to the top of the manual order.
@@ -440,7 +431,6 @@ async def create_note():
             title=clean_title,
             display_title=derive_display_title(clean_title, body),
             body=body,
-            kind=kind,
             color=normalize_color(data.get("color")),
             position=int(max_pos) + 1,
         )
@@ -486,8 +476,6 @@ async def update_note(note_id: str):
             note.body = data["body"]
         if "color" in data:
             note.color = normalize_color(data["color"])
-        if "kind" in data and data["kind"] in ("text", "list"):
-            note.kind = data["kind"]
         if "pinned" in data:
             note.pinned = bool(data["pinned"])
         if "archived" in data: