Fix Ollama settings on startup + video extraction UX

AI provider:
- Extract configureAIProvider() from saveSettings for reuse
- Call it on app startup after sidecar is ready (was only called on Save)
- Call it after first-time sidecar download completes
- Sidecar now receives correct Ollama URL/model immediately

Video extraction:
- Hide ffmpeg console window on Windows (CREATE_NO_WINDOW flag)
- Show "Extracting audio from video..." overlay with spinner during extraction
- UI stays responsive while ffmpeg runs

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

src/lib/stores/settings.ts

@@ -52,11 +52,7 @@ export async function loadSettings(): Promise<void> {
   }
 }
 
-export async function saveSettings(s: AppSettings): Promise<void> {
-  settings.set(s);
-  await invoke('save_settings', { settings: s });
-
-  // Configure the AI provider in the Python sidecar
+export async function configureAIProvider(s: AppSettings): Promise<void> {
   const configMap: Record<string, Record<string, string>> = {
     openai: { api_key: s.openai_api_key, model: s.openai_model },
     anthropic: { api_key: s.anthropic_api_key, model: s.anthropic_model },
@@ -68,7 +64,15 @@ export async function saveSettings(s: AppSettings): Promise<void> {
     try {
       await invoke('ai_configure', { provider: s.ai_provider, config });
     } catch {
-      // Sidecar may not be running yet — provider will be configured on first use
+      // Sidecar may not be running yet
     }
   }
 }
+
+export async function saveSettings(s: AppSettings): Promise<void> {
+  settings.set(s);
+  await invoke('save_settings', { settings: s });
+
+  // Configure the AI provider in the Python sidecar
+  await configureAIProvider(s);
+}