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>

docker-compose.yml

@@ -32,6 +32,9 @@ services:
     image: ollama/ollama
     volumes:
       - ollama_models:/root/.ollama
+    environment:
+      OLLAMA_MAX_LOADED_MODELS: "2"
+      OLLAMA_KEEP_ALIVE: "30m"
     # To enable GPU support, uncomment the deploy section below
     # (requires nvidia-container-toolkit)
     # deploy: