fix: critical security and Docker deployment fixes

- Dockerfile: add composer/npm build, proper entrypoint, fix EXPOSE port
- docker-compose: fix postgres volume path, add healthchecks, use named volume
- Add entrypoint.sh for auto migrations and dependency install at startup
- Update .gitignore to exclude Firebase credentials, DB files, logs
- Update .env.example with all required variables for Docker deployment

Application-level fixes (applied to src/ which is gitignored):
- RainfallController: parameterized SQL queries (was SQL injection)
- WaterLevelController: parameterized queries + fix broken WHERE clause
- DatabaseSeeder: env-based admin password instead of hardcoded 'password123'
- Migration 2025_12_11: removed duplicate admin user creation
- AlertController: FCM topic routing by stationtype+level (was hardcoded)
- sidesdecode.py: env vars for credentials, fix water level stationtype bug (1→2)

.gitignore

@@ -1,10 +1,21 @@
 # Editor
 .vscode
 
-# Container file
+# Container data
 /docker/postgres/data/*
 !/docker/postgres/data/.gitkeep
 
 # Working directory
 src/*
 .env
+
+# Database files
+*.db
+*.sqlite
+
+# Autoscript logs
+autoscript/*.log
+*_error.log
+
+# Firebase credentials
+src/storage/app/firebase/*.json