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/models/note.py

@@ -32,7 +32,13 @@ class Note(Base):
     body: Mapped[str] = mapped_column(Text, default="")
     tags: Mapped[list[str]] = mapped_column(ARRAY(Text), default=list)
     parent_id: Mapped[int | None] = mapped_column(
-        nullable=True
+        Integer, ForeignKey("notes.id", ondelete="SET NULL"), nullable=True
+    )
+    project_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("projects.id", ondelete="SET NULL"), nullable=True
+    )
+    milestone_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("milestones.id", ondelete="SET NULL"), nullable=True
     )
     status: Mapped[str | None] = mapped_column(Text, nullable=True)
     priority: Mapped[str | None] = mapped_column(Text, nullable=True)
@@ -51,6 +57,8 @@ class Note(Base):
         Index("ix_notes_status", "status"),
         Index("ix_notes_title", "title"),
         Index("ix_notes_user_id", "user_id"),
+        Index("ix_notes_project_id", "project_id"),
+        Index("ix_notes_milestone_id", "milestone_id"),
     )
 
     @property
@@ -64,6 +72,8 @@ class Note(Base):
             "body": self.body,
             "tags": self.tags or [],
             "parent_id": self.parent_id,
+            "project_id": self.project_id,
+            "milestone_id": self.milestone_id,
             "status": self.status,
             "priority": self.priority,
             "due_date": self.due_date.isoformat() if self.due_date else None,