feat: Knowledge view + entity types (People, Places, Lists)

Data model:
- Migration 0036: adds note_type TEXT (default 'note') and metadata JSONB
  to the notes table; index on note_type
- Note model: entity_type property, note_type/metadata in to_dict()
- create_note() accepts note_type and metadata params

Backend:
- /api/knowledge — unified paginated endpoint: type/tag/sort/q filters,
  semantic search via embeddings, excludes tasks
- /api/knowledge/tags — distinct tags across knowledge objects
- New LLM tools: create_person, create_place, create_list, add_to_list,
  clear_checked_items — all wired into execute_tool()
- People and places auto-injected as compact summary into LLM system prompt

Frontend:
- KnowledgeView replaces HomeView at /; left filter panel (type+tag),
  toolbar (search, sort, graph toggle), card grid with type-aware cards
  (indigo=note, emerald=person, amber=place, sky=list), load-more pagination
- Today bar: upcoming events, overdue task count, Briefing/Chat links
- Floating mini-chat sticky to bottom: creates/continues a conversation
  inline, message history expands upward, close button ends session
- Graph panel: toggles as a 420px right panel at full viewport width
- AppHeader: Knowledge, Chat, Briefing, Calendar, Tasks, Projects
- Router: / → KnowledgeView; /knowledge redirect; HomeView import removed

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

src/fabledassistant/services/llm.py

@@ -515,14 +515,17 @@ async def build_context(
     tz_line = f" The user's timezone is {user_timezone}." if user_timezone else ""
 
     from fabledassistant.services.user_profile import build_profile_context
+    from fabledassistant.services.knowledge import get_people_and_places_context
     profile_context = await build_profile_context(user_id)
     profile_section = f"\n\n{profile_context}" if profile_context else ""
+    entities_context = await get_people_and_places_context(user_id)
+    entities_section = f"\n\n{entities_context}" if entities_context else ""
 
     system_parts = [
         f"You are a helpful assistant named {assistant_name}, integrated into a note-taking and task-tracking app called Fabled Assistant. "
         "Help users with their notes, tasks, and general questions. "
         "When note context is provided, use it to give relevant answers. "
-        f"Today's date is {today}.{tz_line}{profile_section}\n\n"
+        f"Today's date is {today}.{tz_line}{profile_section}{entities_section}\n\n"
         f"{tool_guidance}"
     ]