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/content/docs/install.mdx

@@ -0,0 +1,33 @@
+---
+title: Install
+description: Install OpenChamber for desktop, web, or VS Code.
+---
+
+# Install
+
+OpenChamber has three main surfaces:
+
+- desktop app for macOS
+- CLI-hosted web app with installable PWA
+- VS Code extension
+
+## Prerequisite
+
+Install [OpenCode](https://opencode.ai) first.
+
+## Web + PWA
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/openchamber/openchamber/main/scripts/install.sh | bash
+openchamber --ui-password be-creative-here
+```
+
+Then open the URL printed by the CLI (usually `http://localhost:3000`).
+
+## Desktop
+
+Download the latest desktop build from the GitHub releases page or the OpenChamber download page.
+
+## VS Code
+
+Install from the VS Code Marketplace and sign into your usual OpenCode workflow.