Add streaming status UX and model load state indicator

Streaming status transparency:
- generation_task.py emits 'status' SSE events at each pipeline stage:
  "Analyzing your request..." before intent classification, tool label
  before each tool execution, "Generating/Composing response..." before
  each LLM streaming round
- chat.ts adds streamingStatus ref; cleared on first chunk or done/error;
  includes fast 5s poll loop after warmModel() until model shows as loaded
- ChatView.vue shows pulsing dot + italic status label above content area;
  falls back to blinking cursor once content arrives
- HomeView.vue shows status label in dashboard panel instead of '...'

Model load state indicator:
- /api/chat/status now queries /api/tags and /api/ps in parallel to
  distinguish installed-but-cold vs loaded-in-VRAM model states
- New model status values: 'not_found' | 'cold' | 'loaded' (was 'ready')
- chatReady true for both 'cold' and 'loaded' (cold models still work)
- AppHeader shows 5 states: gray pulse (checking), red (Ollama down),
  orange (not installed), yellow pulse (cold), green (loaded)
- Inline short label ("Cold", "Ready", "Offline", etc.) visible without
  hovering; detailed tooltip on hover

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

frontend/src/types/chat.ts

@@ -42,6 +42,6 @@ export interface ContextMeta {
 
 export interface OllamaStatus {
   ollama: "available" | "unavailable";
-  model: "ready" | "not_found";
+  model: "loaded" | "cold" | "not_found";
   default_model: string;
 }