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.

src/main.ts

@@ -0,0 +1,8 @@
+import '@fontsource-variable/jetbrains-mono'
+import '@fontsource-variable/schibsted-grotesk'
+import { createPinia } from 'pinia'
+import { createApp } from 'vue'
+import App from './App.vue'
+import './style.css'
+
+createApp(App).use(createPinia()).mount('#app')