feat: add GitHub repository dashboard with Prometheus metrics

ghtracker authenticates as a GitHub App and scans a configured list of repositories on a schedule. It serves a dashboard, a JSON state endpoint, a health probe and Prometheus metrics.

The dashboard lists only items that need attention: failing workflows, pull requests that wait too long or fail their checks, stale issues and projects that failed to scan. It has search, dynamic filters and a button that rescans on demand. The Vue app is embedded in the Go binary.

The client protects the GitHub rate limit with conditional requests, a request reserve and Retry-After handling.

components.json

@@ -0,0 +1,19 @@
+{
+  "$schema": "https://shadcn-vue.com/schema.json",
+  "style": "new-york",
+  "typescript": true,
+  "tailwind": {
+    "config": "",
+    "css": "src/style.css",
+    "baseColor": "neutral",
+    "cssVariables": true
+  },
+  "aliases": {
+    "components": "@/components",
+    "composables": "@/composables",
+    "utils": "@/lib/utils",
+    "ui": "@/components/ui",
+    "lib": "@/lib"
+  },
+  "iconLibrary": "lucide"
+}