chore: init gsd

.gitignore

@@ -17,3 +17,42 @@ auth.json
 
 # dev-fresh launcher scratch (fresh-user sim): disposable per launch
 .fresh-data/
+
+# ── GSD baseline (auto-generated) ──
+.gsd
+.gsd-worktrees/
+.gsd-backups/
+.gsd-id
+.mcp.json
+.bg-shell/
+.claude/settings.local.json
+Thumbs.db
+nul
+nul.*
+con
+con.*
+prn
+prn.*
+aux
+aux.*
+com[1-9]
+com[1-9].*
+lpt[1-9]
+lpt[1-9].*
+*.swp
+*.swo
+*~
+.idea/
+.vscode/
+*.code-workspace
+!.env.example
+build/
+__pycache__/
+*.pyc
+.venv/
+venv/
+target/
+vendor/
+coverage/
+.cache/
+tmp/