Fix project/milestone association and redesign AppHeader navigation

Backend:
- routes/tasks.py: POST + PUT were silently dropping project_id,
  milestone_id, parent_id from request body — root cause of association
  not saving from the task editor
- routes/tasks.py: GET /api/tasks/:id now includes parent_title in
  response (secondary lookup when parent_id is set)
- routes/notes.py: add PATCH /api/notes/:id for partial updates (used
  by sub-task status toggle; PUT already existed but PATCH was missing)
- routes/projects.py: GET /api/projects/:id/notes now fetches milestone
  IDs and passes them via milestone_ids so tasks assigned to a milestone
  (but lacking project_id) are included in the project view
- services/notes.py: create_note() auto-sets project_id from milestone
  when milestone_id is provided and project_id is omitted; list_notes()
  gains milestone_ids param — when combined with project_id uses OR
  condition (project_id=X OR milestone_id IN (...))

Frontend:
- NoteEditorView: add MilestoneSelector; milestone resets when project
  changes; all save paths (save/create/auto-save) include milestone_id
- stores/notes.ts: add milestone_id to createNote + updateNote types
- TaskEditorView: sub-tasks now inherit milestone_id from parent task
- AppHeader: three-zone layout — brand left, Notes/Projects/Tasks/Chat
  centered (absolute positioning), right rail with status/theme/? and
  gear dropdown containing Settings/Users/Logs; mobile dropdown unchanged

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/services/notes.py

@@ -33,6 +33,17 @@ async def create_note(
     priority: str | None = None,
     due_date: date | None = None,
 ) -> Note:
+    # Auto-populate project_id from milestone when not explicitly provided
+    if milestone_id is not None and project_id is None:
+        from fabledassistant.models.milestone import Milestone
+        async with async_session() as lookup:
+            result = await lookup.execute(
+                select(Milestone).where(Milestone.id == milestone_id, Milestone.user_id == user_id)
+            )
+            ms = result.scalars().first()
+            if ms is not None:
+                project_id = ms.project_id
+
     async with async_session() as session:
         note = Note(
             user_id=user_id,
@@ -71,6 +82,7 @@ async def list_notes(
     due_after: date | None = None,
     project_id: int | None = None,
     milestone_id: int | None = None,
+    milestone_ids: list[int] | None = None,
     parent_id: int | None = None,
     sort: str = "updated_at",
     order: str = "desc",
@@ -125,8 +137,13 @@ async def list_notes(
             count_query = count_query.where(Note.due_date >= due_after)
 
         if project_id is not None:
-            query = query.where(Note.project_id == project_id)
-            count_query = count_query.where(Note.project_id == project_id)
+            if milestone_ids:
+                # OR: directly assigned to project, OR assigned to one of the project's milestones
+                project_filter = or_(Note.project_id == project_id, Note.milestone_id.in_(milestone_ids))
+            else:
+                project_filter = Note.project_id == project_id
+            query = query.where(project_filter)
+            count_query = count_query.where(project_filter)
 
         if milestone_id is not None:
             query = query.where(Note.milestone_id == milestone_id)