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/routes/projects.py

@@ -4,6 +4,7 @@ import logging
 from quart import Blueprint, jsonify, request
 
 from fabledassistant.auth import login_required, get_current_user_id
+from fabledassistant.services.milestones import list_milestones
 from fabledassistant.services.notes import list_notes
 from fabledassistant.services.projects import (
     create_project,
@@ -101,11 +102,15 @@ async def get_project_notes_route(project_id: int):
     elif type_filter == "note":
         is_task = False
 
+    ms_list = await list_milestones(uid, project_id)
+    milestone_ids = [m.id for m in ms_list]
+
     notes, total = await list_notes(
         uid,
         is_task=is_task,
         status=status_filter,
         project_id=project_id,
+        milestone_ids=milestone_ids,
         limit=limit,
         offset=offset,
         sort="updated_at",