fix: clean setup probe timeout/error handling

[lan17]

Summary

Tightens setup test-connection behavior and cleans up related test code.

What Changed

• src/homesec/services/setup.py

  • Removed unused cause parameter/state from SetupTestConnectionRequestError.
  • Renamed ONVIF-specific timeout cap constant to be explicit:
    • _TEST_CONNECTION_TIMEOUT_CAP_S -> _ONVIF_TEST_CONNECTION_TIMEOUT_CAP_S.
  • Refined plugin probe timeout/error handling to distinguish phases:
    • plugin load timeout/failure
    • plugin ping timeout/failure
  • Updated logs and user-facing probe messages to reflect the exact failing phase.

• tests/homesec/test_api_setup_routes.py

  • Cleaned import/type usage to avoid duplicate setup model import pattern and keep lint/format clean.

Why

• Improves operator/debug experience by making timeout/failure messages actionable (load vs ping).
• Removes dead/unused error constructor complexity.
• Keeps naming aligned with actual scope (ONVIF-only cap).

Validation

• make check
  • Python: ruff, ruff format --check, mypy --strict, pytest all pass.
  • UI: pnpm check passes.

Scope

• No API contract changes.
• No behavioral changes outside setup test-connection error/timeout reporting clarity.

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.85%. Comparing base (9b29b13) to head (11cbea0).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/homesec/services/setup.py	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #33      +/-   ##
==========================================
- Coverage   82.89%   82.85%   -0.05%     
==========================================
  Files         107      107              
  Lines        9652     9658       +6     
==========================================
+ Hits         8001     8002       +1     
- Misses       1651     1656       +5     

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