BUG-6: Add TLS support via axum-server + rustls
- Added axum-server with tls-rustls feature to workspace and pm-web
- pm-web now serves HTTPS when TLS certs exist, falls back to HTTP with warning
- setup.sh generates self-signed ECDSA P-256 TLS cert with SANs
- Config already had web_tls_cert_path/web_tls_key_path fields
BUG-7: Fix audit chain integrity errors
- Migration 005 now TRUNCATEs audit_log after adding prev_hash column
- Existing rows had broken hash chains (inserted before prev_hash existed)
BUG-8: Disable WatchdogSec in patch-manager-web.service
- pm-web does not implement sd_notify, causing systemd to kill the service
BUG-9: Disable WatchdogSec in patch-manager-worker.service
- Same issue as BUG-8, worker does not implement sd_notify
Previous fixes (BUG-1 through BUG-5) also included:
- setup.sh: PostgreSQL 15+ schema GRANTs
- Axum route syntax :param → {param} (19 routes)
- DbUser struct role: String → UserRole enum mapping
- UserRole/AuthProvider Display trait implementations
- Seed admin password hash (Argon2id)
