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>

alembic/versions/0036_add_note_type_and_metadata.py

@@ -0,0 +1,28 @@
+"""Add note_type and metadata columns to notes table for entity types."""
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects.postgresql import JSONB
+
+revision = "0036"
+down_revision = "0035"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "notes",
+        sa.Column("note_type", sa.Text(), nullable=False, server_default="note"),
+    )
+    op.add_column(
+        "notes",
+        sa.Column("metadata", JSONB(), nullable=True),
+    )
+    op.create_index("ix_notes_note_type", "notes", ["note_type"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_notes_note_type", table_name="notes")
+    op.drop_column("notes", "metadata")
+    op.drop_column("notes", "note_type")