Add settings page, model management, and chat UX improvements

- Settings infrastructure: key-value settings table, GET/PUT API, Pinia store
- Configurable assistant name (default "Fable") in settings and LLM system prompt
- Model catalog with 18 models in 3 categories (General Purpose, Coding,
  Uncensored / Creative Writing) with download/select/remove functionality
- Move Ollama status indicator from chat views to global nav bar
- Chat bubble layout: user messages right-aligned, assistant left-aligned
- Floating dark input bar with auto-focus and circular send button
- Fix HTML entity rendering (' apostrophe issue in marked/DOMPurify pipeline)
- Fix new chat button navigation (fetchConversation before router.push)
- Recent chats section on home page with "New Chat" button
- Update summary.md with Phase 4.5 changes

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

src/fabledassistant/app.py

@@ -7,6 +7,7 @@ from fabledassistant.config import Config
 from fabledassistant.routes.api import api
 from fabledassistant.routes.chat import chat_bp
 from fabledassistant.routes.notes import notes_bp
+from fabledassistant.routes.settings import settings_bp
 from fabledassistant.routes.tasks import tasks_bp
 
 STATIC_DIR = Path(__file__).parent / "static"
@@ -20,6 +21,7 @@ def create_app() -> Quart:
     app.register_blueprint(api)
     app.register_blueprint(chat_bp)
     app.register_blueprint(notes_bp)
+    app.register_blueprint(settings_bp)
     app.register_blueprint(tasks_bp)
 
     @app.before_serving