GitHub Action for automatic decision analysis on PR merge

[Artkill24]

Automatically analyze and document decisions when PRs are merged.

Proposed Behavior

When PR merges to main:

1. Run DevMemory analysis on new commits
2. Post summary as PR comment
3. Optionally update DECISIONS.md file
4. Tag decisions by milestone/release

Implementation

• Create .github/workflows/devmemory.yml
• Use Python action
• Run on pull_request close (merged)
• Comment using GitHub API

Value

• Zero-effort documentation
• Team awareness of decisions
• Historical context always available

Label this as: enhancement, automation