Bound Gemini no-progress tool loops

[Anteriousis]

Stop Gemini after three repeated identical tool observations with unchanged CAD state, including alternating stalled calls and repeated errors. Productive revisions reset the guard; explicit pending-job polls remain allowed within a new 64-request default turn ceiling. Both stops return actionable completion text and preserve completed work.

The issue's requested bounded behavior is enabled by default. Existing callers can explicitly set max_turns=None (or 0) for unlimited turns and no_progress_limit=0 to disable the new guard. The observation table is bounded to 128 entries.

Verification

• Tests failed before implementation and pass afterward.
• Exact test/build commands and results are listed below.

With the local pytest dependencies on PYTHONPATH, using the bundled Python executable:

& $python -m pytest -q src/Mod/VibeCAD/vibecad_tests/test_gemini_provider.py -k 'finite_default or stalled_calls' --tb=short
# Red: 5 failed, 3 passed, 9 deselected.
& $python -m pytest -q src/Mod/VibeCAD/vibecad_tests/test_gemini_provider.py src/Mod/VibeCAD/vibecad_tests/test_provider_subprocess.py --tb=short
# Green: 68 passed, 1 skipped (platform-specific).
& $python -m py_compile src/Mod/VibeCAD/VibeCADProvider.py
git diff --check

Focused mocked-provider tests cover repeated successes/errors, unknown tools, alternating calls, changing revisions, pending polls, and explicit opt-out. No paid API calls or full FreeCAD GUI/C++ build were run. A long legitimate workflow can hit the ceiling; callers can raise or disable it.

Compatibility

• Existing public functions and parameters remain available.
• No preference keys, tool names, or schemas renamed or removed.
• Defaults preserve unlimited loops: intentionally changed as authorized by the request to fix Bound Gemini no-progress tool loops before they consume repeated API calls #176; explicit opt-outs retain that behavior.
• No deprecations.
• Behavioral changes and migration/rollback options are documented above.

Issues

Closes #176.

Before and After Images

Not applicable; no GUI layout changes.