feat(donate): add donate UI

- rework form core and migrate all old usages

app/api/donate/hb/route.ts

@@ -0,0 +1,10 @@
+import { sse } from "@/lib/db/sse-endpoints";
+import { NextRequest } from "next/server";
+
+export async function PATCH(req: NextRequest) {
+  const tag = Number(req.nextUrl.searchParams.get("tag") ?? "abc");
+  if (Number.isNaN(tag))
+    return Response.json({ error: "Invalid Tag" }, { status: 400 });
+  sse.donate.pub("heartbeat", tag);
+  return Response.json({ success: true });
+}

app/api/tts/route.ts

@@ -0,0 +1,77 @@
+import { GoogleGenAI } from "@google/genai";
+import wav from "wav";
+import { Readable, PassThrough } from "stream";
+import z from "zod";
+import { env } from "process";
+import { redis } from "@/lib/db/redis";
+import { hash } from "bun";
+
+const Schema = z.object({
+  message: z.string().max(1000),
+});
+
+const voices = ["Zephyr", "Charon", "Fenrir", "Kore", "Sulafat"];
+
+export async function GET(request: Request) {
+  const data = Schema.safeParse(
+    Object.fromEntries(new URL(request.url).searchParams.entries()),
+  );
+  if (data.error)
+    return new Response(z.prettifyError(data.error), { status: 400 });
+  const {
+    data: { message },
+  } = data;
+
+  const textHash = hash(message).toString(36);
+  const cached = await redis!.get(`tts:${textHash}`);
+  if (cached)
+    return new Response(pcmToWav(cached), {
+      headers: { "Content-Type": "audio/wav" },
+    });
+
+  const client = new GoogleGenAI({ apiKey: env.GEMINI_TTS_API_KEY });
+
+  const response = await client.models.generateContent({
+    model: "gemini-2.5-flash-preview-tts",
+    contents: [{ parts: [{ text: message }] }],
+    config: {
+      responseModalities: ["AUDIO"],
+      speechConfig: {
+        voiceConfig: {
+          prebuiltVoiceConfig: {
+            voiceName: voices[Math.floor(Math.random() * voices.length)],
+          },
+        },
+      },
+    },
+  });
+
+  const audioData =
+    response.candidates?.[0].content?.parts?.[0].inlineData?.data;
+  if (!audioData)
+    return Response.json({ error: "Response is empty" }, { status: 500 });
+  queueMicrotask(() => {
+    redis!.setex(`tts:${textHash}`, 604800, audioData);
+  });
+  return new Response(pcmToWav(audioData), {
+    headers: { "Content-Type": "audio/wav" },
+  });
+}
+
+function pcmToWav(audioData: string) {
+  const audioBuffer = Buffer.from(audioData, "base64");
+  const pcmStream = Readable.from([audioBuffer]);
+  const writer = new wav.Writer({
+    channels: 1,
+    sampleRate: 24000,
+    bitDepth: 16,
+  });
+
+  const out = new PassThrough();
+
+  pcmStream.pipe(writer);
+  writer.on("data", (chunk) => out.write(chunk));
+  writer.on("end", () => out.end());
+  writer.on("error", () => out.end());
+  return Readable.toWeb(out) as unknown as globalThis.ReadableStream;
+}