fix server typecheck: use tsconfig project references, await bun file in spa fallback

- split tsconfig.json into project references (client + server) so bun-types and DOM types don't leak into the other side; server now resolves Bun.* without diagnostics
- client tsconfig adds vite/client types so import.meta.env typechecks
- index.tsx spa fallback: use async/await + c.html(await …) instead of returning a Promise of a Response, which Hono's Handler type rejects
- subtitles normalize-titles: narrow canonical to string|null (Map.get widened to include undefined)

server/api/subtitles.ts

@@ -594,7 +594,7 @@ app.post("/normalize-titles", (c) => {
 
 	let normalized = 0;
 	for (const r of titleRows) {
-		const canonical = canonicalByLang.get(r.language);
+		const canonical = canonicalByLang.get(r.language) ?? null;
 		if (r.title === canonical) continue;
 
 		// Find all streams matching this language+title and set custom_title on their decisions

server/index.tsx

@@ -49,13 +49,12 @@ app.use("/favicon.ico", serveStatic({ path: "./dist/favicon.ico" }));
 // ─── SPA fallback ─────────────────────────────────────────────────────────────
 // All non-API routes serve the React index.html so TanStack Router handles them.
 
-app.get("*", (c) => {
-	const _accept = c.req.header("Accept") ?? "";
+app.get("*", async (c) => {
 	if (c.req.path.startsWith("/api/")) return c.notFound();
 	// In dev the Vite server handles the SPA. In production serve dist/index.html.
 	try {
-		const html = Bun.file("./dist/index.html").text();
-		return html.then((text) => c.html(text));
+		const html = await Bun.file("./dist/index.html").text();
+		return c.html(html);
 	} catch {
 		return c.text("Run `bun build` first to generate the frontend.", 503);
 	}