feat: add auto-merge for PRs passing CI and review score

[jonit-dev]

Summary

Add autoMerge configuration option to automatically merge PRs that pass CI checks and meet the review score threshold. This enables a fully hands-off PRD-to-merge pipeline.

Features

• autoMerge config field (default: false, off by default for safety)
• autoMergeMethod config field (squash|merge|rebase, default: squash)
• --auto-merge CLI flag to enable for a single run
• NW_AUTO_MERGE and NW_AUTO_MERGE_METHOD env vars for override
• Uses gh pr merge --auto --delete-branch to respect branch protection rules
• pr_auto_merged notification event type for webhook integration
• Auto-merge status shown in status command and review --dry-run

Configuration Example

{
  "autoMerge": true,
  "autoMergeMethod": "squash"
}

CLI Usage

# Enable auto-merge for a single run
night-watch review --auto-merge

# View auto-merge status
night-watch status
night-watch review --dry-run

Behavior

• Auto-merge triggers when all open PRs have passing CI AND review score >= threshold
• Uses --auto flag which queues the merge (respects branch protection rules)
• Failures are logged but don't fail the reviewer run
• Only targets PRs matching branchPatterns (same filter as reviewer)

Closes #16

[jonit-dev]

Night Watch PR Fix

Merge Conflicts Resolved:

Rebased onto main. Resolved conflicts in:

• src/tests/commands/review.test.ts
• src/tests/commands/status.test.ts
• src/config.ts
• src/constants.ts
• src/types.ts
• src/utils/notify.ts
• templates/night-watch.config.json

Changes made:

• Kept both the QA/Slack/fallback features from main and the auto-merge feature from this PR
• Fixed duplicate declarations in constants.ts
• Fixed extra closing braces in config.ts

yarn verify passes locally. Ready for re-review.

---

Night Watch PR Reviewer