Refactor supervisor to use environment variables and simplify binary

- Created scripts/generate_secret.sh to generate supervisor secrets
- Added .env.example with all configuration options
- Created scripts/environment.sh to load env vars from .env
- Updated scripts/run.sh to use env vars and pass as flags
- Simplified supervisor binary:
  - Removed bootstrap-admin-key and config file support
  - Made admin-secret required
  - Minimal output (only URLs)
  - Clean startup with no verbose logging
- Updated .gitignore for .env and log files

.gitignore

@@ -1,2 +1,4 @@
 target
-.bin
+.bin
+.env
+/tmp/supervisor-*.log