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.

contexts/ci-cd.md

@@ -0,0 +1,80 @@
+# CI/CD & Release Workflow
+
+## Workflows
+
+| File | Trigger | Purpose |
+|------|---------|---------|
+| `.gitea/workflows/test.yml` | Push/PR to master | Lint (ruff) + pytest |
+| `.gitea/workflows/release.yml` | Tag `v*` | Build artifacts + create Gitea release |
+
+## Release Pipeline (`release.yml`)
+
+Four parallel jobs triggered by pushing a `v*` tag:
+
+### 1. `create-release`
+Creates the Gitea release with a description table listing all artifacts. **The description must stay in sync with actual build outputs** — if you add/remove/rename an artifact, update the body template here.
+
+### 2. `build-windows` (cross-built from Linux)
+- Runs `build-dist-windows.sh` on Ubuntu with NSIS + msitools
+- Downloads Windows embedded Python 3.11 + pip wheels cross-platform
+- Bundles tkinter from Python MSI via msiextract
+- Builds frontend (`npm run build`)
+- Pre-compiles Python bytecode (`compileall`)
+- Produces: **`LedGrab-{tag}-win-x64.zip`** (portable) and **`LedGrab-{tag}-setup.exe`** (NSIS installer)
+
+### 3. `build-linux`
+- Runs `build-dist.sh` on Ubuntu
+- Creates a venv, installs deps, builds frontend
+- Produces: **`LedGrab-{tag}-linux-x64.tar.gz`**
+
+### 4. `build-docker`
+- Plain `docker build` + `docker push` (no Buildx — TrueNAS runners lack nested networking)
+- Registry: `{gitea_host}/{repo}:{tag}`
+- Tags: `v0.x.x`, `0.x.x`, and `latest` (stable only, not alpha/beta/rc)
+
+## Build Scripts
+
+| Script | Platform | Output |
+|--------|----------|--------|
+| `build-dist-windows.sh` | Linux → Windows cross-build | ZIP + NSIS installer |
+| `build-dist.sh` | Linux native | tarball |
+| `server/Dockerfile` | Docker | Container image |
+
+## Release Versioning
+
+- Tags: `v{major}.{minor}.{patch}` for stable, `v{major}.{minor}.{patch}-alpha.{n}` for pre-release
+- Pre-release tags set `prerelease: true` on the Gitea release
+- Docker `latest` tag only applied to stable releases
+- Version in `server/pyproject.toml` should match the tag (without `v` prefix)
+
+## CI Runners
+
+- Two TrueNAS Gitea runners with `ubuntu` tags
+- No Windows runner available — Windows builds are cross-compiled from Linux
+- Docker Buildx not available (networking limitations) — use plain `docker build`
+
+## Test Pipeline (`test.yml`)
+
+- Installs `opencv-python-headless` and `libportaudio2` for CI compatibility
+- Display-dependent tests are skipped via `@requires_display` marker
+- Uses `python` not `python3` (Git Bash on Windows resolves `python3` to MS Store stub)
+
+## Common Tasks
+
+### Creating a release
+```bash
+git tag v0.2.0
+git push origin v0.2.0
+```
+
+### Creating a pre-release
+```bash
+git tag v0.2.0-alpha.1
+git push origin v0.2.0-alpha.1
+```
+
+### Adding a new build artifact
+1. Update the build script to produce the new file
+2. Add upload step in the relevant `build-*` job
+3. **Update the release description** in `create-release` job body template
+4. Test with a pre-release tag first