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/views/HomeView.vue

@@ -360,7 +360,11 @@ function clearDashboardResponse() {
 
           <!-- Streaming text -->
           <div v-if="chatStore.streaming" class="dashboard-response-text streaming">
-            <span v-if="chatStore.streamingContent">{{ chatStore.streamingContent }}</span>
+            <div v-if="chatStore.streamingStatus && !chatStore.streamingContent" class="dashboard-status-line">
+              <span class="dashboard-status-dot"></span>
+              {{ chatStore.streamingStatus }}
+            </div>
+            <span v-else-if="chatStore.streamingContent">{{ chatStore.streamingContent }}</span>
             <span v-else class="thinking-dots">...</span>
           </div>
           <!-- Final text -->
@@ -553,6 +557,21 @@ function clearDashboardResponse() {
   display: inline-block;
   animation: blink 1.2s infinite;
 }
+.dashboard-status-line {
+  display: flex;
+  align-items: center;
+  gap: 0.4rem;
+  font-style: italic;
+}
+.dashboard-status-dot {
+  display: inline-block;
+  width: 6px;
+  height: 6px;
+  border-radius: 50%;
+  background: var(--color-primary);
+  animation: blink 1.2s infinite;
+  flex-shrink: 0;
+}
 @keyframes blink {
   0%, 100% { opacity: 1; }
   50% { opacity: 0.3; }