feat(bankai): bankai v10 — the isomorphic compiler & server on Vite 8

One command, zero config, and only the client ever bundles: v8 server
code is plain ESM that Node runs as-authored, so there is no server
build to rot (the lesson of v9).

- start: Vite middleware mode + HMR with per-request streaming SSR via
  ssrLoadModule; a virtual client entry generates the browser glue so
  the user writes exactly one isomorphic module (plan decision D5).
- build: client bundle via Vite 8/Rolldown, manifest-derived route
  assets in dist/bankai.json, service worker built with the precache
  list injected (choo-service-worker convention, manifest edition),
  brotli+gzip precompression of every text asset.
- serve: immutable caching + precompressed negotiation for hashed
  assets, 103 Early Hints (res.writeEarlyHints) with the route's assets
  before every page, streaming SSR, and a window.initialState tail with
  script-breakout-safe serialization and choo internals filtered out.
- inspect: raw/gzip/brotli size report.

Integration tests drive the real counter example through build and
serve, asserting the 103 interim response at the HTTP level.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014NgfSjHE11oFpoSnLVKLXd

packages/bankai/lib/app.js

@@ -0,0 +1,23 @@
+// The isomorphic entry contract (plan decision D5): the entry module's
+// default export is either a choo app instance (typically
+// `export default app.mount('body')` — mount() on the server records the
+// selector and returns the app) or a factory returning one (preferred:
+// fresh state per request). One module, three consumers: browser mount,
+// server render, build metadata.
+
+export function resolveApp (mod, entry) {
+  const value = mod && mod.default
+  if (!value) {
+    throw new Error(`bankai: ${entry} has no default export — export your choo app (or a function returning one)`)
+  }
+  // a factory is a plain function; an app instance has .mount
+  const app = typeof value === 'function' && !value.mount ? value() : value
+  if (typeof app.toStream !== 'function') {
+    throw new Error(`bankai: the default export of ${entry} is not a choo v8 app (missing toStream)`)
+  }
+  return app
+}
+
+export function selectorOf (app) {
+  return app.selector || 'body'
+}