Add model selection, dashboard chat input, and model warming

- Add GET /api/chat/ps and POST /api/chat/warm endpoints for hot model
  visibility and pre-loading
- Extend PATCH /api/chat/conversations/:id to accept model in addition
  to title
- Add ModelSelector component with hot/cold indicators from Ollama /api/ps
- Add DashboardChatInput component (model selector + note picker + textarea)
  replacing the simple "New Chat" button on the dashboard
- Add model selector dropdown to ChatView header, persisted per-conversation
- Warm default model on dashboard mount via fire-and-forget background task
- Configure Ollama with OLLAMA_MAX_LOADED_MODELS=2 and OLLAMA_KEEP_ALIVE=30m
- Always-visible edit buttons on NoteCard/TaskCard (remove hover-only behavior)

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

src/fabledassistant/services/llm.py

@@ -80,7 +80,7 @@ async def stream_chat(
     payload: dict = {"model": model, "messages": messages, "stream": True}
     if options:
         payload["options"] = options
-    async with httpx.AsyncClient(timeout=httpx.Timeout(300.0, connect=10.0)) as client:
+    async with httpx.AsyncClient(timeout=httpx.Timeout(1800.0, connect=10.0, read=300.0)) as client:
         async with client.stream(
             "POST",
             f"{Config.OLLAMA_URL}/api/chat",
@@ -100,7 +100,7 @@ async def stream_chat(
 
 async def generate_completion(messages: list[dict], model: str) -> str:
     """Non-streaming chat completion, returns full response text."""
-    async with httpx.AsyncClient(timeout=httpx.Timeout(300.0, connect=10.0)) as client:
+    async with httpx.AsyncClient(timeout=httpx.Timeout(1800.0, connect=10.0, read=300.0)) as client:
         resp = await client.post(
             f"{Config.OLLAMA_URL}/api/chat",
             json={"model": model, "messages": messages, "stream": False},