docs: add CI/CD context file and pre-commit lint rule

Create contexts/ci-cd.md documenting release pipeline, build scripts,
CI runners, and versioning. Reference it from CLAUDE.md context table.
Add mandatory pre-commit lint check rule to CLAUDE.md.

CLAUDE.md

@@ -38,6 +38,7 @@ ast-index changed --base master           # Show symbols changed in current bran
 | [contexts/graph-editor.md](contexts/graph-editor.md) | Visual graph editor changes |
 | [contexts/server-operations.md](contexts/server-operations.md) | Server restart, startup modes, demo mode |
 | [contexts/chrome-tools.md](contexts/chrome-tools.md) | Chrome MCP tool usage for testing |
+| [contexts/ci-cd.md](contexts/ci-cd.md) | CI/CD pipelines, release workflow, build scripts |
 | [server/CLAUDE.md](server/CLAUDE.md) | Backend architecture, API patterns, common tasks |
 
 ## Task Tracking via TODO.md
@@ -64,9 +65,15 @@ This applies to: file paths in `StorageConfig`, JSON root keys (e.g. `picture_ta
 
 **Incident context:** A past rename of `picture_targets.json` → `output_targets.json` was done without migration. The app created a new empty `output_targets.json` while the user's 7 targets sat unread in the old file. Data was silently lost.
 
-## CI/Release Workflow
+## Pre-Commit Checks (MANDATORY)
 
-When modifying the release workflow (`.gitea/workflows/release.yml`), **always keep the release description body in sync with actual build artifacts**. If you add/remove/rename a build artifact (ZIP, installer, tarball, Docker image), update the release description table in the `create-release` job to match.
+Before every commit, run the relevant linters and fix any issues:
+
+- **Python changes**: `cd server && ruff check src/ tests/ --fix`
+- **TypeScript changes**: `cd server && npx tsc --noEmit && npm run build`
+- **Both**: Run both checks
+
+Do NOT commit code that fails linting. Fix the issues first.
 
 ## General Guidelines