Slice 1: surface system + WS transport + composition root

Pure-core feature libraries assembled at the composition root:
- core/protocol: pure reducer over surface catalog/spec/error messages
- features/surface-host: generic field-kind interpreter (toggle/progress/
  selector/stat/button) + pure plan logic; no surface-id special-casing
- adapters/ws: injected WebSocket client (effects at the edge)
- app: composition root store (Svelte 5 runes over the pure reducer),
  host-relative surface WS URL resolution (resolveWsUrl), root App.svelte

Verified green: svelte-check 0/0, vitest 84 passed, biome clean, vite build ok.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main.ts b/src/main.ts
new file mode 100644
index 0000000..f58cfe2
--- /dev/null
+++ b/src/main.ts
@@ -0,0 +1,9 @@
+import { mount } from "svelte";
+import App from "./App.svelte";
+
+const target = document.getElementById("app");
+if (!target) {
+	throw new Error("missing #app mount target");
+}
+
+export default mount(App, { target });