Harden JetBrains inspection proof verdicts

[cbusillo]

Summary

This hardens the JetBrains inspection helper against false-green readiness results by making compact proof failures override a plugin/helper GREEN verdict, and by preserving nested .idea project paths as exact route targets instead of collapsing them to the parent git worktree.

What changed

• Treat proof_failures as verdict-source data copied through summaries.
• Return UNKNOWN with inspection_proof_failed when proof contradictions are present, even if the plugin says GREEN and total_problems is 0.
• Preserve nested .idea project paths in build_context() as project_path / exact_route_path.
• Use exact_route_path for route sorting, route diagnostics, and exact route verification.
• Add regression tests for nested .idea routing, proof-failure summary propagation, and human verdict behavior.

Validation

uv run jetbrains-inspection/tests/test_jb_inspect.py
# Ran 116 tests ... OK

Refs cbusillo/jetbrains-inspection-api#113
Refs cbusillo/jetbrains-inspection-api#114
Refs #388