Add Projects, Milestones, RAG auto-inject, push notifications, PWA, tag normalisation

## Projects & Milestones (Phases A + G)
- New models: Project, Milestone (Project → Milestone → Task hierarchy)
- notes table: project_id + milestone_id FKs; parent_id FK constraint activated
- Migrations: 0017 (projects), 0018 (push_subscriptions), 0019 (events), 0020 (milestones)
- Services: projects.py, milestones.py (CRUD + progress tracking)
- Routes: /api/projects + /api/projects/<id>/milestones
- LLM tools: create/list/get/update project; create/list milestone; project + milestone + parent_task params on note/task tools
- Frontend: ProjectListView (stacked milestone bars), ProjectView (milestone-grouped kanban), ProjectSelector, MilestoneSelector, NoteEditorView + TaskEditorView updated

## RAG Auto-injection (Phase B)
- Notes ≥0.60 cosine similarity auto-injected into system prompt (max 3, 800 chars each)
- excluded_note_ids param; ChatView "Auto-included" sidebar section

## Summarisation improvements (Phase C)
- Threshold 20→30, keep-recent 6→8, max_tokens 200→400
- Two-pass summarisation for histories >50 messages

## Browser push notifications (Phase E)
- PushSubscription model + migration; pywebpush dependency
- /api/push routes; VAPID config; fire-and-forget on generation complete
- Frontend: sw.js, push store, Settings toggle

## PWA manifest (Phase F)
- manifest.json, Apple meta tags, service worker registration in main.ts

## Tag normalisation
- All tags lowercased + deduplicated at backend (create_note/update_note) and frontend (TagInput sanitize)
- Note/Task types gain project_id + milestone_id fields; store signatures updated

## CalDAV
- Radicale embedded server reverted; back to user-configured external CalDAV

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

src/fabledassistant/routes/notes.py

@@ -84,6 +84,8 @@ async def create_note_route():
         body=body,
         tags=tags,
         parent_id=data.get("parent_id"),
+        project_id=data.get("project_id"),
+        milestone_id=data.get("milestone_id"),
         status=status,
         priority=priority,
         due_date=due_date,
@@ -176,7 +178,7 @@ async def update_note_route(note_id: int):
     uid = get_current_user_id()
     data = await request.get_json()
     fields = {}
-    for key in ("title", "body", "parent_id", "status", "priority"):
+    for key in ("title", "body", "parent_id", "project_id", "milestone_id", "status", "priority"):
         if key in data:
             fields[key] = data[key]