Add unit and integration test suites

- Shared: link building, feed ordering, input schemas, API client
- API unit: track matching, private-address blocking, token crypto,
  plan expiry, provider response parsing
- API integration against Postgres and Redis: auth, follows and pins,
  now-playing state, webhooks, OAuth return URLs, realtime, rate limits
- Tests use a dedicated *_test database and Redis DB, and refuse to wipe
  anything else; fetch is stubbed so they never hit the network
- Pin Node to 22.13+ (.nvmrc), which Vite's native bindings require

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/api/src/providers/match.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, it } from 'vitest';
+import { findBestMatch } from './match';
+
+const target = { title: 'Midnight City', artist: 'M83', durationMs: 243_000 };
+
+describe('findBestMatch', () => {
+  it('prefers the exact title with a matching duration', () => {
+    const best = findBestMatch(
+      [
+        { id: 'remix', title: 'Midnight City (Eric Prydz Remix)', artist: 'M83', durationMs: 400_000 },
+        { id: 'cover', title: 'Midnight City', artist: 'Party Machine', durationMs: 243_000 },
+        { id: 'real', title: 'Midnight City', artist: 'M83', durationMs: 244_000 },
+      ],
+      target,
+    );
+    expect(best?.id).toBe('real');
+  });
+
+  it('rejects other artists even with the same title', () => {
+    expect(findBestMatch([{ title: 'Midnight City', artist: 'Some Cover Band' }], target)).toBeNull();
+  });
+
+  it('rejects durations more than 15s apart', () => {
+    expect(findBestMatch([{ title: 'Midnight City', artist: 'M83', durationMs: 300_000 }], target)).toBeNull();
+  });
+
+  it('matches when either side lacks a duration', () => {
+    expect(findBestMatch([{ title: 'Midnight City', artist: 'M83' }], { title: 'Midnight City', artist: 'M83' })).not.toBeNull();
+  });
+
+  it('tolerates featured-artist and remaster suffixes', () => {
+    const best = findBestMatch([{ title: 'Midnight City - Remastered', artist: 'M83, Someone' }], target);
+    expect(best).not.toBeNull();
+  });
+});