fix(llmloop): finalize exhausted reviews

[4-1-1]

Description

When a per-file review reaches its context-tool round budget, the loop currently stops immediately unless the model already called task_done. A text-only response also retries with the full context tool set, which can reopen investigation instead of converging.

Add a two-round terminal-only finalization phase after either condition. The model can only submit code_comment findings and finish with task_done, so gathered evidence is preserved without allowing more context expansion. Explicit successful task_done remains the only completion signal.

Automated Review Reproduction

The PR's OpenCodeReview check reproduced the existing behavior with the published v1.8.10 binary: reviewing only internal/llmloop/loop.go made 19 context-expansion calls (8 code_search, 11 file_read), consumed 175,414 tokens, and timed out after 10 minutes without calling task_done.

This check intentionally runs the trusted base-branch action and installs the published latest package under pull_request_target; it does not execute the implementation from this fork. The regular CI, race tests, and cross-compilation checks pass on the PR code.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring (no functional changes)
• Documentation update
• CI / Build / Tooling

How Has This Been Tested?

• make test passes locally
• Manual testing (describe below)

Additional verification:

• make check
• make build
• focused llmloop, agent, scan, and CLI tests

Checklist

• My code follows the project coding style (go fmt, go vet)
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or my feature works
• New and existing unit tests pass locally with my changes
• Documentation is unchanged because no user-facing option or output format changes
• I have signed the CLA

Related Issues

No linked issue.