feat: replace Playwright extractor with yt-dlp subprocess

- Add instagram-extractor.ts: yt-dlp subprocess backend for Instagram
  caption extraction. No in-process browser state, maintained against
  Instagram frontend churn, supports cookies.txt for auth-walled reels.
- Add feature flag EXTRACTOR_BACKEND (ytdlp|playwright) in QueueProcessor
  so the old Playwright path remains available as fallback.
- Add 9 unit tests and 2 live-network integration tests for the new extractor.
- Dockerfile: install yt-dlp via pip3 alongside existing Chromium deps.
- docker-compose: expose EXTRACTOR_BACKEND env var (default: ytdlp).

Also in this commit:
- LLM: configurable per-request timeout via LLM_REQUEST_TIMEOUT_MS (default 120s);
  set maxRetries=0 to surface errors immediately; llama-swap /running health probe.
- QueueProcessor: thread progress callback through parser phase.
- LlmHealthIndicator: surface llama-swap loaded-model name.
- Logging: improve error serialization in queue-processor tests.
- .env.example: document llama-swap endpoint and model options.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/routes/share/components/LlmHealthIndicator.svelte

@@ -1,9 +1,12 @@
 <script lang="ts">
 	import { onMount } from 'svelte';
 
+	type HealthStatus = 'checking' | 'ok' | 'warming' | 'error';
+
 	interface HealthState {
-		status: 'checking' | 'healthy' | 'unhealthy' | 'error';
+		status: HealthStatus;
 		message: string;
+		configuredModel: string;
 		lastChecked: Date | null;
 	}
 
@@ -14,6 +17,7 @@
 	let health = $state<HealthState>({
 		status: 'checking',
 		message: '',
+		configuredModel: '',
 		lastChecked: null
 	});
 
@@ -21,24 +25,26 @@
 		try {
 			const res = await fetch('/api/llm-health');
 			const data = await res.json();
+			const status: HealthStatus =
+				data.status === 'ok' ? 'ok' : data.status === 'warming' ? 'warming' : 'error';
 			health = {
-				status: data.status === 'healthy' ? 'healthy' : 'unhealthy',
-				message: data.message,
+				status,
+				message: data.message ?? '',
+				configuredModel: data.configuredModel ?? '',
 				lastChecked: new Date()
 			};
 		} catch (e) {
 			health = {
 				status: 'error',
 				message: e instanceof Error ? e.message : 'Network error',
+				configuredModel: '',
 				lastChecked: new Date()
 			};
 		}
 	}
 
-	// Use onMount instead of $effect for timer-based side effects
-	// onMount only runs in browser, no SSR guard needed
 	onMount(() => {
-		checkHealth(); // Initial check
+		checkHealth();
 		const interval = setInterval(checkHealth, pollInterval);
 		return () => clearInterval(interval);
 	});
@@ -48,12 +54,12 @@
 	<div class="flex items-center gap-1">
 		{#if health.status === 'checking'}
 			🟡 <span>Checking LLM...</span>
-		{:else if health.status === 'healthy'}
+		{:else if health.status === 'ok'}
 			🟢 <span class="text-green-600">LLM Ready</span>
-		{:else if health.status === 'unhealthy'}
-			🔴 <span class="text-red-600">LLM Unavailable</span>
+		{:else if health.status === 'warming'}
+			🟡 <span class="text-yellow-600">LLM Cold ({health.configuredModel})</span>
 		{:else}
-			🔴 <span class="text-red-600">LLM Error</span>
+			🔴 <span class="text-red-600">LLM Unavailable</span>
 		{/if}
 	</div>
 	<div class="text-xs text-gray-500" title={health.message}>