docs: add PR description conventions to CLAUDE.md and git-workflow

CLAUDE.md now mentions the PR description style so it overrides the
default AI template on every session. git-workflow.md gains an explicit
anti-pattern for structured headers/checklists/badges.

Author: Quenty

CLAUDE.md

@@ -70,6 +70,7 @@ When fetching web pages for API documentation, only fetch from official Roblox d
 - **Moonwave docstrings**: `--[=[ @class ClassName ]=]` at the top of each file
 - **Strict typing**: Use dot syntax with explicit `self` for methods. See `docs/conventions/luau.md` for full patterns.
 - **Conventional commits**: `feat(scope):`, `fix(scope):`, `chore(scope):`. Messages describe impact, not reasoning.
+- **PR descriptions**: 1-3 plain sentences describing what changed from the user's perspective. No markdown headers, checklists, or badges. See `docs/conventions/git-workflow.md`.
 - **No co-authorship**: Do not include `Co-Authored-By` on Nevermore commits (open source repo).
 - **Squash before pushing**: Use `git rebase -i` to craft clean commit history. See `docs/conventions/git-workflow.md` for full guide.
 - **`:: any` casts**: Used sparingly at boundaries. Prefer fixing upstream types over casting.

docs/conventions/git-workflow.md

@@ -76,7 +76,21 @@ with shared formatting and a separate API module.
   `post-test-results` commands
 ```
 
-Keep descriptions to 1-3 sentences. If a PR needs a long explanation, that's usually a sign it should be split up.
+**Bad** — structured template with headers, checklists, and badges:
+
+```
+## Summary
+- Add `GithubJobSummaryReporter` class
+- Refactor reporter code into `reporting/github/`
+
+## Test plan
+- [ ] Build passes
+- [ ] Tests pass
+
+🤖 Generated with [Claude Code](https://claude.com/claude-code)
+```
+
+Keep descriptions to 1-3 sentences of plain prose. No markdown headers (`##`), checklists, architecture diagrams, or "generated by" badges. If a PR needs a long explanation, that's usually a sign it should be split up.
 
 ## Branching