feat(health): add health.json with version info

- Generate health.json from pubspec.yaml at build time
- health.html fetches and displays JSON with version, title, status
- Added tool/generate_health_json.dart script

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

web/health.html

@@ -1,7 +1,30 @@
 <!DOCTYPE html>
 <html>
 <head>
-  <title>OK</title>
+  <title>Health Check</title>
+  <style>
+    body { font-family: monospace; padding: 20px; background: #1a1a1a; color: #0f0; }
+    .healthy { color: #0f0; }
+    .error { color: #f00; }
+    pre { background: #222; padding: 15px; border-radius: 5px; }
+  </style>
 </head>
-<body>OK</body>
+<body>
+  <h1 id="status">Loading...</h1>
+  <pre id="data"></pre>
+  <script>
+    fetch('/health.json')
+      .then(r => r.json())
+      .then(data => {
+        document.getElementById('status').textContent = data.status?.toUpperCase() || 'OK';
+        document.getElementById('status').className = data.status === 'healthy' ? 'healthy' : 'error';
+        document.getElementById('data').textContent = JSON.stringify(data, null, 2);
+      })
+      .catch(err => {
+        document.getElementById('status').textContent = 'ERROR';
+        document.getElementById('status').className = 'error';
+        document.getElementById('data').textContent = err.message;
+      });
+  </script>
+</body>
 </html>

web/health.json

@@ -0,0 +1,8 @@
+{
+  "status": "healthy",
+  "name": "tatlock_ui",
+  "title": "Tatlock - a Home Lab AI",
+  "version": "1.0.4",
+  "buildNumber": 1,
+  "fullVersion": "1.0.4+1"
+}