feat: add inline project timeline and notes section to Project Detail

- Implemented a Gantt timeline using GanttChart component scoped to project checkpoints.
- Added functionality to create and manage checkpoints with AddCheckpointDialog.
- Introduced EditCheckpointDialog for editing existing checkpoints.
- Created a notes section displaying a list of notes with the ability to add new notes.
- Updated routing to include notes detail page.
- Enhanced GanttChart with context menu for editing and deleting checkpoints.
- Improved UI components for better user experience.

DEFAULT_PROMPT.md

@@ -23,20 +23,20 @@ APPEND to progress.txt (never replace, always append):
 
 ## USER REQUEST
 {
-  "id": "US-014",
-  "title": "Kanban board in Project Detail",
-  "description": "As a user, I want a Kanban board inside the project detail view with drag-and-drop task management between status columns.",
+  "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.",
   "acceptanceCriteria": [
-    "@hello-pangea/dnd installed; DragDropContext wraps 3 Droppable columns: To Do | In Progress | Completed",
-    "Each task card is a Draggable wrapped in a shadcn/ui Card rendering: title, description (truncated), priority as shadcn/ui Badge, due date chip, assignee string",
-    "Dragging a card to another column calls tasks.update({ id, status }) via tRPC and the UI updates immediately (optimistic or on success)",
-    "'+ Add' shadcn/ui Button (variant=ghost, size=sm) in each column header opens the shadcn/ui Dialog new-task modal with the column's status pre-selected",
-    "Columns show a task count in their header using shadcn/ui Badge (variant=secondary)",
-    "All card content uses shadcn/ui primitives: Card, Badge, Button (already installed)",
+    "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)",
     "Typecheck passes",
     "Verify in browser using dev-browser skill"
   ],
-  "priority": 14,
+  "priority": 15,
   "passes": false,
   "notes": ""
 }