Add status page enhancements with new metrics and footer

- Add GC statistics (run count, total/last pause, heap usage)
- Add BGP peer count tracking from RIS Live OPEN/NOTIFICATION messages
- Add route churn rate metric (announcements + withdrawals per second)
- Add announcement and withdrawal counters
- Add footer with attribution, license, and git revision
- Embed git revision at build time via ldflags
- Update HTML template to display all new metrics

internal/version/version.go

@@ -0,0 +1,34 @@
+// Package version provides build version information
+package version
+
+// Build-time variables set via ldflags
+//
+//nolint:gochecknoglobals // These must be variables to allow ldflags injection at build time
+var (
+	// GitRevision is the git commit hash
+	GitRevision = "unknown"
+	// GitRevisionShort is the short git commit hash (7 chars)
+	GitRevisionShort = "unknown"
+)
+
+const (
+	// Name is the program name
+	Name = "routewatch"
+	// Author is the program author
+	Author = "@sneak"
+	// AuthorURL is the author's website
+	AuthorURL = "https://sneak.berlin"
+	// License is the program license
+	License = "WTFPL"
+	// RepoURL is the git repository URL
+	RepoURL = "https://git.eeqj.de/sneak/routewatch"
+)
+
+// CommitURL returns the URL to view the current commit
+func CommitURL() string {
+	if GitRevision == "unknown" {
+		return RepoURL
+	}
+
+	return RepoURL + "/commit/" + GitRevision
+}