[OpenClaw] chore: add .gitignore for static site

.gitignore

@@ -0,0 +1,24 @@
+# macOS
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Linux
+*~
+
+# Editor
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# Node (if tooling added later)
+node_modules/
+dist/
+.env
+.env.local
+
+# Python (if tooling added later)
+__pycache__/
+*.pyc
+.venv/

SDD.md

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+# SDD: Add .gitignore for sdd-learn (Static HTML / GitHub Pages)
+
+## Goal
+Add a `.gitignore` to prevent OS metadata, editor files, and potential future build artifacts from appearing in `git status`.
+
+## Scope
+
+### In
+- Add `.gitignore` with macOS, editor, and light tooling patterns
+
+### Out
+- No changes to index.html
+
+## Approach
+Single-page static site (index.html only). No `.gitignore` currently. Same rationale as other static sites: prevent .DS_Store, editor workspace files, and future tooling artifacts from leaking into commits.
+
+## Change List
+
+| File | Change | Why |
+|------|--------|-----|
+| `.gitignore` | Create new file | Prevent OS/editor artifacts from being tracked |
+
+## Tests
+- `git check-ignore -v .DS_Store` — must match
+- `git status` — must show only `.gitignore` as new file
+
+### Results
+✅ All checks passed — .DS_Store matched, git status clean
+
+## Rollback
+Delete `.gitignore`. No other changes.
+
+## Risk Notes
+- Zero risk. No currently-tracked files affected.