feat: harden model library + worker reconnect lifecycle and fix compose GUI backend

[rwilliamspbg-ops]

Summary

This PR now includes full real GUI/API wiring, model lifecycle hardening, worker lifecycle resilience, and compose/CI verification improvements.

Scope

1. Complete real GUI-to-backend wiring (no GUI fallback placeholders for core flows).
2. Harden model library + HuggingFace onboarding behavior.
3. Harden worker join/leave/reconnect and slice failover behavior.
4. Upgrade compose/CI verification to actually smoke-test GUI-facing services.

What Changed

Real GUI Wiring

• GUI actions are now backed by concrete API endpoints for:
  • model listing/loading/downloading
  • worker listing/adding/connecting
  • queue actions
  • chat inference
  • session listing/cancel
  • security actions (JWT refresh, PQC enable)
• Removed placeholder/fallback behavior for core data paths in mohawk_gui/main_window.py.
• Added latency bar updates and worker/session count updates driven by API responses.

Controller Service (GUI Backend)

• Added and expanded prototype/controller_service.py with in-memory state and endpoints:
  • GET /health
  • GET /api/models
  • POST /api/models/load
  • POST /api/models/download
  • GET /api/workers
  • POST /api/workers/add
  • POST /api/workers/connect
  • POST /api/queue
  • POST /api/inference/chat
  • GET /api/metrics
  • GET /api/sessions
  • POST /api/sessions/{session_id}/cancel
  • POST /api/security/jwt/refresh
  • POST /api/security/pqc/enable
• Improved worker URL parsing robustness and runtime health checks.

Model + Worker Hardening

• Persistent model library index support and local/HF registration.
• Safer HF loading/download argument handling.
• Worker lifecycle ops: join/leave/reconnect.
• Slice cache re-share/failover behavior for worker transitions.
• Deterministic key derivation and secure payload/manifest handling updates.
• Shape-preserving NPZ slice serialization with fallback compatibility.

Compose and Docker Wiring

• Main compose stack now runs real controller backend wiring for GUI usage.
• Dev compose controller runs real API service instead of placeholder command.
• Dockerfiles updated to include required runtime modules for controller service.

CI / Verification

• Added compose smoke test job in CI to:
  • build and start compose stack
  • wait for service health
  • verify GUI-facing endpoints with HTTP checks
  • dump logs on failure and clean up

Tests and Validation

• Full test suite: 87 passed, 4 skipped
• New controller-service endpoint tests added:
  • tests/test_controller_service.py (all passing)
• Compose configs validated:
  • docker compose -f docker-compose.yml config
  • docker compose -f docker-compose.dev.yml config

Notes for Reviewers

Primary files to review:

• mohawk_gui/main_window.py
• prototype/controller_service.py
• tests/test_controller_service.py
• docker-compose.yml
• docker-compose.dev.yml
• .github/workflows/ci.yml

Risk

• Main residual risk is runtime-only container behavior in environments different from CI/dev setup.
• Mitigation: compose smoke job plus expanded endpoint-level tests.