feat(gacha): add /api/gacha wish animation rendered as MP4

A meteor coloured by rarity falls across a night sky, lands in a white
flash, and the label is revealed with its stars popping in. The caller
picks the result and rarity; the route only draws it. Renders as silent
H.264 so Telegram plays it as an animation without GIF banding, and
shares the render slots with /api/gif.

renderer/test/gacha-request.test.js

@@ -0,0 +1,32 @@
+import {describe, expect, test} from 'vitest';
+import {parseGachaRequest} from '../src/schemas/gacha-request.js';
+
+const limits = {maxOptionChars: 12};
+
+describe('parseGachaRequest', () => {
+  test('trims the label and applies defaults', () => {
+    const request = parseGachaRequest({label: ' Pizza ', rarity: 5}, limits);
+
+    expect(request).toEqual({label: 'Pizza', rarity: 5, fps: 24, width: 640});
+  });
+
+  test('accepts the larger frame and fps', () => {
+    const request = parseGachaRequest({label: 'Pho', rarity: 4, fps: 30, width: 854}, limits);
+
+    expect(request.fps).toBe(30);
+    expect(request.width).toBe(854);
+  });
+
+  test.each([
+    {label: 'Pizza', rarity: 2},
+    {label: 'Pizza', rarity: 6},
+    {label: 'Pizza'},
+    {label: '   ', rarity: 3},
+    {label: 'x'.repeat(13), rarity: 3},
+    {label: 'Pizza', rarity: 3, width: 512},
+    {label: 'Pizza', rarity: 3, fps: 15},
+    {label: 'Pizza', rarity: 3, extra: true},
+  ])('rejects %o', (input) => {
+    expect(() => parseGachaRequest(input, limits)).toThrow();
+  });
+});