feat(hybridz): complete frontend solver integration

[Kaijie-liu]

PR7 Summary

This final PR in the HybridZ completes the command line and end-to-end integration. It does not modify the HybridZ representation, operators, mathematical encoding, or verdict solver.

1. Automatically select HybridzTF

Previously, running:

--solvers hybridz

could still leave the default interval transformer active. The HybridZ solver would then receive no HybridZ state and return:

UNKNOWN: missing_hz_state

The standalone HybridZ solver now automatically selects the required pipeline:

HybridzTF propagation -> HybridZ solver verdict

Users no longer need to also specify --tf-modes hybridz.

2. Apply consistent mode selection across pipeline entry points

act/pipeline/cli.py now uses one shared mode-resolution path for:

• VNNLIB
• TorchVision
• NetFactory

For NetFactory sweeps, the standalone HybridZ solver runs only once with HybridzTF, avoiding duplicate runs caused by multiple requested TF modes.

3. Forward the verification timeout

The pipeline option:

--timeout 120

is now forwarded to the HybridZ verdict solver. When the deadline is reached, HybridZ returns UNKNOWN; its existing no-rescue behavior remains unchanged.

4. Align the backend CLI

The backend command:

python -m act.back_end ... --solver hybridz

now automatically activates HybridzTF. If an incompatible mode such as --tf-mode interval is explicitly supplied, the CLI emits a warning and uses HybridzTF.

5. Update CLI documentation

The existing help text and examples now clarify that:

• HybridZ is a solver.
• It automatically selects HybridzTF.
• End-to-end HybridZ verification requires only --solvers hybridz.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.18%. Comparing base (8c41b8b) to head (77f700a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #99      +/-   ##
==========================================
- Coverage   73.19%   73.18%   -0.01%     
==========================================
  Files          92       92              
  Lines       20268    20268              
==========================================
- Hits        14835    14834       -1     
- Misses       5433     5434       +1     

Flag	Coverage Δ
bab	45.28% <ø> (-0.01%)	⬇️
backend-float32	48.83% <ø> (ø)
backend-float64	48.87% <ø> (ø)
frontend	32.41% <ø> (ø)
pipeline-fuzz	20.21% <ø> (ø)
pipeline-verify	38.98% <ø> (ø)

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see 1 file with indirect coverage changes

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[yuleisui]

This needs to be merged into #96

[Kaijie-liu]

This needs to be merged into #96

Understood. I have ported these changes to the #96 through guanqin-123#4 (guanqin-123#4).