Add failing tests for #533: Orchestrator doesn't validate duplicate issue resolution status

[prompt-driven-github]

Summary

Adds failing tests that detect the bug reported in #533 where the orchestrator blindly trusts LLM duplicate detection without validating that the original issue is actually resolved.

Test Files

• Unit test: tests/test_issue_533_duplicate_validation.py (10 tests)
• E2E test: tests/test_e2e_issue_533_duplicate_validation.py (3 tests)

What This PR Contains

• Failing unit tests that reproduce the reported bug in various scenarios
• Failing E2E tests that verify the bug at integration level with real prompt loading
• Tests are verified to fail on current code and will pass once the bug is fixed

Root Cause

The bug is at pdd/agentic_bug_orchestrator.py:441 where the orchestrator checks for the string "Duplicate of #" but doesn't validate whether the original issue is actually resolved. When the LLM fails to follow prompt instructions and outputs "Duplicate of #520" even though #520 is still OPEN, the orchestrator incorrectly triggers a hard stop and closes the duplicate issue.

Test Results on Current Code

• Unit tests: 8 failures (detecting bug), 2 passes (regression tests)
• E2E tests: 2 failures (detecting bug), 1 pass (regression test)

Next Steps

1. Implement the fix at pdd/agentic_bug_orchestrator.py:441
2. Add validation to check if the original issue is resolved before triggering hard stop
3. Verify all unit tests pass
4. Verify all E2E tests pass
5. Run full test suite for regression checks
6. Mark PR as ready for review

Fixes #533

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