Fix: PR number extraction regex to handle format variations

Summary

Fix PR number extraction from ticket comments to handle variations in formatting (colons, spaces, etc.).

Problem (Bug #5 from #167)

Ticket #2 execution showed:

✓ Pull Request: #18 - Ready for review
✗ Error executing #2: Developer failed to create PR

PR #18 was created successfully, but CLI marked ticket as failed because it couldn't extract the PR number.

Impact:

• False failures block workflow
• Successful tickets marked as failed
• Sprint execution stops prematurely

Root Cause

Developer commented: **Pull Request:** #18 - Ready for review

CLI regex: r"(?:Pull request|PR)\s+#(\d+)"

• Requires space(s) between "PR" and "#"
• Actual comment has colon: "Pull Request: #18"
• Colon breaks the match → extraction fails → ticket marked as failed

Solution

Make regex more flexible to handle common variations:

Location: src/factory/cli.py:1800

# OLD:
pr_match = re.search(r"(?:Pull request|PR)\s+#(\d+)", comment.body, re.IGNORECASE)

# NEW:
pr_match = re.search(
    r"(?:Pull request|PR)[:\s]+#(\d+)",  # Allow colon or spaces
    comment.body,
    re.IGNORECASE
)

This allows:

• ✅ Pull request #18
• ✅ PR #18
• ✅ Pull Request: #18
• ✅ PR: #18
• ✅ Pull request: #18 (multiple spaces)

Test Plan

1. Unit tests for PR extraction:

test_cases = [
    "Pull request #18",
    "PR #18",
    "Pull Request: #18",
    "PR: #18",
    "**Pull Request:** #123 - Ready",
    "Created pull request #456",
]
for comment in test_cases:
    assert extract_pr_number(comment) is not None

1. E2E test:

• Mock Developer agent to post comment with colon format
• Verify CLI successfully extracts PR number
• Verify ticket not marked as failed

Acceptance Criteria

• [ ] Regex updated to r"(?:Pull request|PR)[:\s]+#(\d+)"
• [ ] Unit tests for all format variations
• [ ] All existing tests still pass
• [ ] E2E test with colon format
• [ ] Documentation: Comment format examples

Related Issues

• Fixes Bug #5 in #167
• One-line regex fix

Priority

High - Causes false failures in Stage 2 execution.