feat: bootstrap vela UI and gateway workspace

Establish the monorepo, tooling, and starter apps so UI and gateway development can begin from a documented, runnable baseline.

docs/setup.md

@@ -0,0 +1,72 @@
+# Vela Setup and Workspace Layout
+
+## Tooling and Package Management
+
+- Use **mise** to provision repo tools.
+- Use **Yarn** for dependency management and workspace commands in this repository.
+
+The repo-level tool configuration lives in `mise.toml`.
+
+## Workspace Layout
+
+```text
+apps/
+  vela-ui/
+  vela-gateway/
+docs/
+AGENTS.md
+README.md
+mise.toml
+package.json
+```
+
+## Workspace Purpose
+
+### `apps/vela-ui`
+
+- minimal SvelteKit browser application
+- current starter page confirms the workspace boots correctly
+- intended to grow into the SvelteKit PWA implementation
+
+### `apps/vela-gateway`
+
+- minimal Fastify gateway service
+- current HTTP endpoints provide a runnable baseline at `/` and `/health`
+- intended to grow into the WebSocket session and orchestration layer
+
+## Initial Commands
+
+Install repo tools:
+
+```bash
+mise install
+```
+
+Install dependencies:
+
+```bash
+mise exec -- yarn install
+```
+
+Run the current workspaces:
+
+```bash
+mise exec -- yarn dev:ui
+mise exec -- yarn dev:gateway
+```
+
+Additional verification commands:
+
+```bash
+mise exec -- yarn check:ui
+mise exec -- yarn build:ui
+mise exec -- yarn build:gateway
+```
+
+## Notes
+
+- the concrete framework choices are now SvelteKit for `vela-ui` and Fastify for `vela-gateway`
+- the UI is intentionally minimal and does not yet include mic capture, transcript rendering, or WebSocket session state
+- the gateway is intentionally minimal and does not yet expose the planned WebSocket contract
+- if your shell is configured for mise activation, plain `yarn` commands can be used after `mise install`
+- update this document when the repo layout or package manager workflow changes