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

Makefile

@@ -1,5 +1,11 @@
 export DEBUG = routewatch
 
+# Git revision for version embedding
+GIT_REVISION := $(shell git rev-parse HEAD 2>/dev/null || echo "unknown")
+GIT_REVISION_SHORT := $(shell git rev-parse --short HEAD 2>/dev/null || echo "unknown")
+VERSION_PKG := git.eeqj.de/sneak/routewatch/internal/version
+LDFLAGS := -X $(VERSION_PKG).GitRevision=$(GIT_REVISION) -X $(VERSION_PKG).GitRevisionShort=$(GIT_REVISION_SHORT)
+
 .PHONY: test fmt lint build clean run asupdate
 
 all: test
@@ -15,7 +21,7 @@ lint:
 	golangci-lint run
 
 build:
-	CGO_ENABLED=1 go build -o bin/routewatch cmd/routewatch/main.go
+	CGO_ENABLED=1 go build -ldflags "$(LDFLAGS)" -o bin/routewatch cmd/routewatch/main.go
 
 clean:
 	rm -rf bin/