feat(session): singleton detached worker controls with multiprocessing

[GeorgesAlkhouri]

Summary

• add singleton detached session worker lifecycle with session start|status|exec|stop
• keep legacy docctl session NDJSON stream mode for backward compatibility
• switch worker spawn from subprocess to multiprocessing spawn
• enforce strict singleton config matching to prevent accidental session drift
• add POSIX Unix-socket transport, idle TTL state handling, and stale-state cleanup

Tests

• make format-check
• make typecheck
• make security-lint
• make import-lint
• make check-markdown-links
• make test-cov

Coverage

• service_session_worker.py to 100% coverage via focused branch tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (65cc5ab) to head (a7cc6b2).

Additional details and impacted files

@@            Coverage Diff             @@
##              main       #35    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           23        24     +1     
  Lines         1258      1696   +438     
==========================================
+ Hits          1258      1696   +438     

Flag	Coverage Δ
pytest	100.00% <100.00%> (ø)

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud