Remove BGP keepalive logging and add peer tracking

- Created bgp_peers table to track all BGP peers
- Added PeerHandler to update peer last seen times for all message types
- Removed verbose BGP keepalive debug logging
- BGP keepalive messages now silently update peer tracking

Refactor HTML templates to use go:embed

- Created internal/templates package with embedded templates
- Moved status.html from inline const to separate file
- Templates are parsed once on startup
- Server now uses parsed template instead of raw string

Optimize AS data embedding with gzip compression

- Changed asinfo package to embed gzipped data (2.4MB vs 12MB)
- Updated Makefile to gzip AS data during update
- Added decompression during initialization
- Raw JSON file excluded from git

Makefile

@@ -25,5 +25,5 @@ run: build
 
 asupdate:
 	@echo "Updating AS info data..."
-	@go run cmd/asinfo-gen/main.go > pkg/asinfo/asdata.json.tmp && \
-		mv pkg/asinfo/asdata.json.tmp pkg/asinfo/asdata.json
+	@go run cmd/asinfo-gen/main.go | gzip > pkg/asinfo/asdata.json.gz.tmp && \
+		mv pkg/asinfo/asdata.json.gz.tmp pkg/asinfo/asdata.json.gz