feat: add file-backed canvas notes

Magic Notes previously supported rich-text records without a paged drawing or
PDF annotation workflow. Add the integrated PeopleLib Fabric and Quill editor
with flowing text, pen/highlighter, object transforms, images, paper templates,
PDF backgrounds with native text extraction, and raster PDF export. Saves are
manual; undo/redo remains scoped to an annotation page or Quill mode.

Analyze drafts, saved canvases and canvas-source todos with page images and
text when the default model supports images, or an explicitly labelled
text-only fallback. Keep successful saves when automatic analysis fails and
prevent MCP plain-text replacement of canvas records.

Move entry bodies and binary assets into local note files with schema 38
migration and verified readback. SQLite retains metadata, indexes, revisions,
todos and comments. Backups must coordinate SQLite and the adjacent notes
directory while writes are paused or the app is closed; no one-click backup
action is included.

Show a continuous record stream with independent collapsible record index and
AI pane, real first-page thumbnails, and scroll-only record navigation. Open a
blank text/canvas composer by default and reset it after creation. Protect
unsaved drafts and establish normalized editor baselines after saving so clean
records do not prompt again when leaving.

Validation: latest recorded focused run passed 149 tests across five files;
typecheck, lint and git diff --check passed. The prior user-reported full run
passed 4,713 tests before later corrections and UI changes; it is not a full
validation of this final snapshot. Tests were not rerun for this commit, as
requested; independent systematic review follows the commit.

Release note: Create paged notes with handwriting, flowing text and PDF
annotations, browse records through thumbnails, and request AI comments with
an explicit text-only fallback. Existing notes migrate to local file storage;
backups now need both the database and notes directory.

FEATURES.md

@@ -600,10 +600,15 @@ records are listed separately and do not introduce another feature status.
   cancelled states, and expose cited context or safely open its source.
 - [x] **Magic Notes**: A local-first notes and todo workbench with scope
   management, editing, filtering, and controlled AI comments. Notes open from a
-  responsive card overview. The separate To-dos tab offers search, status filters,
+  responsive card overview. Detail displays a continuous stream with independently
+  collapsible left index and right AI pane. Real first-page thumbnails scroll to
+  records without replacing editors. Successful saves establish the editor's
+   normalized baseline; only unsaved changes require confirmation on leaving. Opening
+   a note shows a blank text/canvas composer above the history, and creation resets it
+   for the next record. Explicit editing updates a saved record. The separate To-dos view offers search, status filters,
   grouped tasks and direct completion, with instructions, source entries and AI
   comments in a right detail pane beside a stable task list. Narrow views offer
-  on-demand detail with an explicit return to the list. Content-sized tabs sit
+  on-demand detail with an explicit return to the list. A content-sized switch sits
   beside New note in the header; status filters follow search. Source-note
   navigation returns to the same task context, without
   showing the previous item's source after a selection change. Failed reads
@@ -611,6 +616,24 @@ records are listed separately and do not introduce another feature status.
   navigation can show the incomplete-todo count, and create, save, and comment
   results use application-wide notifications. Agent/MCP note writes automatically
   refresh the open workbench while preserving selection and unsaved drafts.
+- [x] **Paged canvas notes**: The integrated PeopleLib Fabric + Quill editor
+  combines flowing body text with pen/highlighter, object selection/transforms,
+  floating text, images and paper templates. Import PDFs as page backgrounds
+  with native text extraction, then export a raster PDF of text and annotations;
+  exported PDFs do not retain a searchable text layer. Manual saves store entry
+  bodies and binary assets in local note files; SQLite retains metadata, indexes,
+  revisions, todos and comments. Backups must coordinate SQLite and the notes
+  directory; there is no one-click backup action. Undo/redo
+  is per annotation page or Quill mode, not global document history; there is no
+  infinite canvas or PNG download button. Drafts, saved entries and canvas-source
+  todos use the default model's image-input capability for page images plus text,
+  or an explicitly labelled text-only fallback. Purely visual entries/drafts
+  require an image-capable model. Immediate-comment mode offers manual canvas
+  analysis; after-save automatic analysis failures do not block or undo saving.
+  Text-only comments survive unchanged extracted text; visual comments are
+  invalidated by layout changes and reanalyzed in after-save-auto mode. MCP
+  rejects plain-text replacement of canvas entries. Implementation is complete;
+  final validation status is tracked in the [feature progress record](./docs/features/magic-notes/progress.md).
 - [ ] **MCP Server Control Plane** (planned): Unified MCP lifecycle, health
   checks, reconnection, schema cache, isolation, approval, and audit.
 - [ ] **Traceable note excerpts and AI editing** (planned): Collects sourced