feat(mobile): Skia wave, wave player view, themes and playback settings (M5)

- My Wave is rendered with react-native-skia on the UI thread; physics
  and colour helpers moved to @pipu/core (wave-anim) and shared with web.
- Full-screen player honours ui_prefs.mobile_player (cover / wave).
- Theme switching (dark / light / system) via a theme context and
  useColors() across all screens.
- Profile: theme, wave variant, player view, sound quality sheet
  (Wi-Fi / mobile / downloads), recent-tracks cache clearing on next
  cold start, and a change-password sheet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/mobile/src/offline/downloads.ts

@@ -3,6 +3,7 @@ import { unwrap, type AuthSession, type Track } from '@pipu/core';
 import * as FileSystem from 'expo-file-system';
 import * as SecureStore from 'expo-secure-store';
 
+import { qualityPrefs } from '../lib/prefs';
 import { shortHash } from '../lib/storage';
 import { getDb } from './db';
 
@@ -258,7 +259,8 @@ class Downloads {
         return;
       }
       const part = `${this.file(id)}.part`;
-      const dl = FileSystem.createDownloadResumable(`${this.abs(track.stream_url)}&q=high`, part, {}, (p) => {
+      const q = (await qualityPrefs.load()).download;
+      const dl = FileSystem.createDownloadResumable(`${this.abs(track.stream_url)}&q=${q}`, part, {}, (p) => {
         if (p.totalBytesExpectedToWrite > 0) this.setItem(id, { progress: p.totalBytesWritten / p.totalBytesExpectedToWrite });
       });
       this.active.set(id, dl);