complete bambu-op parity for operator cutover

[voska]

This completes the operator workflow in bambu so its charter and skill can switch without losing functionality.

• Port verified chamber-light control and temporary lighting for camera/monitor snapshots, built-in ntfy configuration/token/attachment handling, continuous monitoring and cadence flags, STEP tessellation, object footprints and suggested-slot metadata.
• Add opt-in strict operator gates and preview requirements while preserving existing Go defaults and output contracts. Add full monitor final state and keep outcome codes correct in continuous mode.
• Verify pause/stop state before success. Reject stale slice output and unexpected tool changes; preserve light restoration on failures and interruption.
• Document the command, configuration and secret-store migration.

Validation: make ci (format, lint: 0 issues, vet, race tests, build); independent review approved after regression tests for missing MQTT ACKs, monitor outcomes/interruption and first-plate footprints. Real Bambu Studio 02.08.02.61 sliced a STEP coupon with a preview and dimensions. Read-only strict two-colour dry run on X1C passed with [3, 0] AMS mapping. A real camera capture verified light off → on → off; status independently confirmed restoration. No print, motion or filament change was sent. Notification lifecycle/failures and attachments are tested against local HTTP fixtures; ntfy is unconfigured locally.