docs: refresh docs and add tunnel usage guide (#666)

Add a new tunnels page with verified, up-to-date CLI examples
Remove deprecated `--daemon` usage and clarify QR/password behavior
Add docs validation tooling and docs-source workflow for packaging and sync

packages/docs/README.md

@@ -0,0 +1,31 @@
+# OpenChamber Docs Source
+
+This package is the source-of-truth for OpenChamber public docs content.
+
+## Layout
+
+- `content/docs/*.mdx` - English docs pages
+- `sidebar.config.json` - docs navigation structure for Starlight sidebar
+- `CONTRIBUTING.md` - authoring guide for adding pages and sections
+- `DEPLOYMENT.md` - release/manual packaging and sync trigger model
+
+## Local validation
+
+Run from repo root:
+
+```bash
+bun run docs:validate
+```
+
+This validates:
+
+- frontmatter (`title`, `description`) exists for every MDX page
+- sidebar links resolve to existing MDX routes
+
+## Deployment model
+
+This repo owns docs content.
+
+Website rendering/deployment happens in `openchamber-website` (`apps/docs`).
+
+Use `.github/workflows/docs-source.yml` to package docs source on release or manual trigger.