Config: add MiniMax direct API authentication option

Makes apiKey optional in ModelProviderConfig so MiniMax can use auth
profiles or environment variables (MINIMAX_API_KEY) instead of requiring
explicit config.

Changes:
- src/config/types.ts: apiKey changed from required to optional
- src/config/zod-schema.ts: use z.string().min(1).optional() for validation
- src/commands/configure.ts: add minimax-api auth choice in wizard
- src/commands/onboard-auth.ts: MiniMax provider omits apiKey (uses env/auth)
- patches/@mariozechner__pi-ai@0.42.1.patch: map minimax → MINIMAX_API_KEY

Auth Resolution Order (unchanged):
1. Auth profiles (highest priority)
2. Environment variables (MINIMAX_API_KEY, etc.)
3. Custom provider apiKey from models.json (lowest priority)

AGENTS.md

@@ -115,3 +115,39 @@ EOF
 ```
 
 This is a Claude Code quirk, not a clawdbot bug.
+
+---
+
+## PR & Code Review Checklist
+
+Before creating PRs or presenting code for review (especially to senior engineers):
+
+### 1. Verify Code Quality
+- [ ] Run `pnpm lint` - no errors
+- [ ] Run `pnpm build` - TypeScript compiles
+- [ ] Run related tests - all pass
+
+### 2. Review Diff Purity
+- [ ] Diff is minimal and focused on the feature
+- [ ] No unrelated changes bundled in
+- [ ] Patch files: **append** changes, don't replace entire files
+
+### 3. Self-Critique Questions
+- Is the auth resolution chain correct?
+- Are type changes safe and backwards compatible?
+- Would this pass review by John Carmack? (clarity > cleverness)
+
+### 4. Fork Workflow (when applicable)
+```bash
+# Push to fork
+git remote add fork https://github.com/USERNAME/clawdbot
+git push fork branch-name
+
+# Create PR from fork
+gh pr create --head USERNAME:branch-name --base main
+```
+
+### 5. Git Diff Interpretation
+- `-` lines = content being **removed**
+- `+` lines = content being **added**
+- Verify you understand what the diff actually shows