feat(ebpf): add nginx HTTP capture infrastructure via kretprobe recvfrom

Add supporting infrastructure for nginx HTTP capture using kretprobe
on __x64_sys_recvfrom to replace the blocked tracepoint sys_exit_recvfrom.

Changes:
- bpf/bpf_types.h: Add nginx_pid_map for filtering recvfrom by PID
- cmd/ja4ebpf/main.go: Add Uprobes configuration section
- Makefile: Add test targets for recvfrom validation
- internal/loader: Generate nginx HTTP event structures

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

services/ja4ebpf/Makefile

@@ -28,6 +28,15 @@ test:
 ## docker-build: Alias combiné generate + build
 docker-build: build
 
+## test-recvfrom-vm: Teste les alternatives recvfrom sur VM Rocky 9
+test-recvfrom-vm:
+	@bash scripts/test-vm-recvfrom.sh rocky9
+
+## test-recvfrom-docker: Teste les alternatives recvfrom dans Docker
+test-recvfrom-docker:
+	@docker build -f Dockerfile.test-recvfrom -t ja4-recvfrom-test ../../
+	@docker run --rm --privileged ja4-recvfrom-test
+
 ## help: Affiche cette aide
 help:
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | \