fix: Docker build failures — backend .dockerignore excluded package.json, frontend lock file missing hls.js

Backend: *.json glob in .dockerignore excluded package.json, causing
npm install to fail with ENOENT. Replaced with explicit exclusions.

Frontend: hls.js was added to package.json but package-lock.json was
not regenerated, causing npm ci to fail with EUSAGE sync error.

backend/.dockerignore

@@ -5,6 +5,12 @@ __pycache__/
 .pytest_cache/
 .coverage
 cctv.db
-*.json
 *.txt
 !requirements.txt
+# Exclude debug/cache JSON but keep package.json and tracked_names
+ais_cache.json
+carrier_positions.json
+dump.json
+debug_fast.json
+nyc_full.json
+nyc_sample.json