update-docslisted

# Update Tesseron docs Keep `docs/src/content/docs/` aligned with whatever just changed in `gateway/**`, `docs-mcp/**`, or SDK source in a language repository. The docs are the published Starlight site and the contract Tesseron users read, so drift here is user-visible. ## Prerequisites - A recent edit to `gateway/**`, `docs-mcp/**`, or SDK source in a language repository (use `git diff` / `git diff --stat HEAD` to see the change set). - The docs tree at `docs/src/content/docs/`. If it's missing, stop and flag it. ## Doc pages and what they own | Page | Owns | |------|------| | `overview/index.mdx` (the root `index.mdx`) | Elevator pitch, hero copy, top-level links. Rarely changes. | | `overview/architecture.mdx` | Three-process model diagram, protocol boundary descriptions. | | `overview/quickstart.mdx` | The 5-minute path: install, declare one action, run the gateway, see Claude call it. | | `overview/why.md` | Positioning vs browser automation / Playwright / chat widgets. | | `protocol/index.mdx` | One-page protocol overview. Update when a new top-level concept lands. | | `protocol/wire-format.mdx` | JSON-RPC envelope, method names, id rules. | | `protocol/transport.md` | WebSocket URL, framing, origin allowlist, reconnect behavior. | | `protocol/handshake.mdx` | `tesseron/hello`, `welcome`, claim code, `tools/list_changed`. | | `protocol/actions.mdx` | Action declaration, namespacing, invoke / validate / return. | | `protocol/progress-cancellation.mdx` | `actions/pro