feat: production-ready firmware with BLE memory management, device_id fixes, and docs

- Reduce debug level to 1 (errors only) for production builds
- Replace BLE pause/resume with full deinit/reinit during HTTP uploads (~25KB freed)
- Add 60s boot report delay for fast post-deploy connectivity verification
- Add device_id to BLE batch and heartbeat request bodies
- Correct API host to http:// (plain HTTP, not HTTPS)
- Add HTTP response logging and CV entry/exit serial logging
- Create root README.md with operator setup and architecture overview
- Update design spec: HMAC format, BLE memory approach, request body shapes, reporting intervals

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

firmware/src/reporter.h

@@ -12,7 +12,7 @@ struct CameraHourlyRecord {
 };
 
 static const int    REPORTER_MAX_BUFFER = 24;
-static const char*  REPORTER_API_HOST   = "https://logs.research.bike";
+static const char*  REPORTER_API_HOST   = "http://logs.research.bike";
 
 void reporter_init();
 void reporter_submit_camera(const DeviceConfig& cfg, const CameraHourlyRecord& rec);