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.

semver.yaml

@@ -0,0 +1,18 @@
+# Read by the shared release workflow (lukaszraczylo/semver-generator).
+version: 1
+
+force:
+  existing: true
+  strict: false
+
+# Fuzzy matching counts stray words such as "majority" as a major bump.
+# Only a `Semver-Major:` trailer line may start a major release.
+matching: regex
+
+wording:
+  patch:
+    - '(?m)^(fix|perf|refactor|revert|build|chore|ci|docs|style|test)(\([^)]*\))?!?:'
+  minor:
+    - '(?m)^feat(\([^)]*\))?!?:'
+  major:
+    - '(?m)^Semver-Major:'