feat: add streamer-owned recording control service

Introduce a dedicated streamer-side recording control plane instead of sharing the producer recorder API.

- register streamer-owned recorder endpoints as a NATS micro service
- add explicit MP4 and MCAP recorder control protobufs and subject helpers
- wire recorder lifecycle handling into the pipeline runtime
- add MP4 writer and depth-alignment support files used by the new recording flow

include/cvmmap_streamer/protocol/streamer_subjects.hpp

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <string>
+#include <string_view>
+
+namespace cvmmap_streamer::protocol {
+
+inline std::string streamer_subject_prefix(std::string_view target_key) {
+	return std::string("cvmmap.") + std::string(target_key) + ".streamer";
+}
+
+inline std::string subject_recorder_mp4_start(std::string_view target_key) {
+	return streamer_subject_prefix(target_key) + ".recorder.mp4.start";
+}
+
+inline std::string subject_recorder_mp4_stop(std::string_view target_key) {
+	return streamer_subject_prefix(target_key) + ".recorder.mp4.stop";
+}
+
+inline std::string subject_recorder_mp4_status(std::string_view target_key) {
+	return streamer_subject_prefix(target_key) + ".recorder.mp4.status";
+}
+
+inline std::string subject_recorder_mcap_start(std::string_view target_key) {
+	return streamer_subject_prefix(target_key) + ".recorder.mcap.start";
+}
+
+inline std::string subject_recorder_mcap_stop(std::string_view target_key) {
+	return streamer_subject_prefix(target_key) + ".recorder.mcap.stop";
+}
+
+inline std::string subject_recorder_mcap_status(std::string_view target_key) {
+	return streamer_subject_prefix(target_key) + ".recorder.mcap.status";
+}
+
+}  // namespace cvmmap_streamer::protocol