feat: integrate Milkdown editor for note-taking functionality

- Added Milkdown dependencies: @milkdown/kit, @milkdown/react, @milkdown/theme-nord.
- Implemented MilkdownEditor component for rich text editing in notes.
- Updated /notes/$noteId route to include editable title and auto-saving functionality.
- Enhanced UI with loading states, saving indicators, and delete confirmation dialog.
- Applied Milkdown-specific CSS overrides for consistent theming and styling.
- Improved note update logic with debounced saving and cleanup on unmount.

DEFAULT_PROMPT.md

@@ -23,20 +23,21 @@ APPEND to progress.txt (never replace, always append):
 
 ## USER REQUEST
 {
-  "id": "US-015",
-  "title": "Inline project timeline and notes list in Project Detail",
-  "description": "As a user, I want to see the project's Gantt timeline and a list of its notes within the project detail scrollable view.",
+  "id": "US-016",
+  "title": "Milkdown note editor",
+  "description": "As a user, I want a full-screen Markdown editor for each note so that I can write rich content without leaving the app.",
   "acceptanceCriteria": [
-    "Project Detail view includes a 'Project Timeline' section using the GanttChart component (from US-012) scoped to the current project's checkpoints",
-    "'+ Add' shadcn/ui Button (variant=outline, size=sm) in the timeline section header opens the add-checkpoint shadcn/ui Dialog with the project pre-selected",
-    "Notes section below Kanban shows a flat list using shadcn/ui Separator between rows: each row has note title + formatted createdAt date",
-    "'+ Add' shadcn/ui Button in notes header calls notes.create with a default title and navigates to /notes/:noteId",
-    "Clicking a note title navigates to /notes/:noteId",
-    "All buttons/dialogs use shadcn/ui components (already installed)",
+    "@milkdown/react and @milkdown/preset-commonmark installed; Milkdown editor renders at route /notes/:noteId",
+    "Supported Markdown: headings (H1-H6), bold, italic, inline code, code blocks, bullet lists, ordered lists, blockquotes",
+    "Note title editable as a shadcn/ui Input (variant borderless/ghost style) at the top of the page (separate from Milkdown content area)",
+    "Content auto-saves to SQLite via notes.update on Milkdown onChange event, debounced 500ms",
+    "Unsaved indicator shown using shadcn/ui Badge (variant=secondary, text 'Saving...') next to the title while save is pending",
+    "Back button uses shadcn/ui Button (variant=ghost, size=icon) with ArrowLeft Lucide icon; navigates to the previous route",
+    "All UI chrome uses shadcn/ui components (already installed)",
     "Typecheck passes",
     "Verify in browser using dev-browser skill"
   ],
-  "priority": 15,
+  "priority": 16,
   "passes": false,
   "notes": ""
 }