refactor(api): co-locate server-protocol clients into lib/api

Move the Subsonic + Navidrome protocol clients and the library IPC facade
(subsonic*, navidrome*, library.ts + tests) from src/api/ into src/lib/api/,
the feature-free infra layer (plan M4, decision §10.3: shared client core → lib/).
Pure move: deep-path import specifiers @/api/* -> @/lib/api/* across ~150
consumers; no behaviour change. Domain REST (lyrics/events) and cover/analysis
infra stay in src/api/ pending their own M4 placement.

tsc 0, lint 0/0, full suite 319 files / 2353 tests green.

src/features/nowPlaying/components/AlbumCard.tsx

@@ -1,7 +1,7 @@
 import React, { memo, useEffect, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { Disc3, ExternalLink, Star } from 'lucide-react';
-import type { SubsonicAlbum, SubsonicSong } from '@/api/subsonicTypes';
+import type { SubsonicAlbum, SubsonicSong } from '@/lib/api/subsonicTypes';
 import { formatTotalDuration } from '@/utils/componentHelpers/nowPlayingHelpers';
 import { formatTrackTime } from '@/utils/format/formatDuration';
 

src/features/nowPlaying/components/ArtistCard.test.tsx

@@ -8,7 +8,7 @@ import { describe, it, expect, vi } from 'vitest';
 import { fireEvent } from '@testing-library/react';
 import { renderWithProviders } from '@/test/helpers/renderWithProviders';
 import ArtistCard from '@/features/nowPlaying/components/ArtistCard';
-import type { SubsonicArtistInfo } from '@/api/subsonicTypes';
+import type { SubsonicArtistInfo } from '@/lib/api/subsonicTypes';
 
 const infoWithImage: SubsonicArtistInfo = {
   biography: 'Some bio text here.',

src/features/nowPlaying/components/ArtistCard.tsx

@@ -1,7 +1,7 @@
 import React, { memo, useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { ExternalLink } from 'lucide-react';
-import type { SubsonicArtistInfo } from '@/api/subsonicTypes';
+import type { SubsonicArtistInfo } from '@/lib/api/subsonicTypes';
 import { isRealArtistImage, sanitizeHtml } from '@/utils/componentHelpers/nowPlayingHelpers';
 import CachedImage from '@/ui/CachedImage';
 

src/features/nowPlaying/components/DiscographyCard.tsx

@@ -1,7 +1,7 @@
 import React, { memo, useEffect, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { Disc3, ExternalLink, Music } from 'lucide-react';
-import type { SubsonicAlbum } from '@/api/subsonicTypes';
+import type { SubsonicAlbum } from '@/lib/api/subsonicTypes';
 import { AlbumCoverArtImage } from '@/cover/AlbumCoverArtImage';
 import { COVER_DENSE_RAIL_CELL_CSS_PX } from '@/cover/layoutSizes';
 

src/features/nowPlaying/components/Hero.tsx

@@ -4,7 +4,7 @@ import { Headphones, Heart, MicVocal, Music, Star } from 'lucide-react';
 import { CoverArtImage } from '@/cover/CoverArtImage';
 import type { CoverArtRef } from '@/cover/types';
 import type { ArtistStats, TrackStats } from '@/music-network';
-import type { SubsonicOpenArtistRef } from '@/api/subsonicTypes';
+import type { SubsonicOpenArtistRef } from '@/lib/api/subsonicTypes';
 import { OpenArtistRefInline } from '@/features/artist';
 import { formatTrackTime } from '@/utils/format/formatDuration';
 import { useEnrichmentPrimaryLabel } from '@/hooks/useEnrichmentPrimaryLabel';

src/features/nowPlaying/components/NowPlayingDropdown.tsx

@@ -1,6 +1,6 @@
 import { TrackCoverArtImage } from '@/cover/TrackCoverArtImage';
-import { getNowPlaying } from '@/api/subsonicScrobble';
-import type { SubsonicNowPlaying } from '@/api/subsonicTypes';
+import { getNowPlaying } from '@/lib/api/subsonicScrobble';
+import type { SubsonicNowPlaying } from '@/lib/api/subsonicTypes';
 import React, { useState, useEffect, useRef, useCallback, useLayoutEffect } from 'react';
 import { createPortal } from 'react-dom';
 import { PlayCircle, Pause, User, Radio, RefreshCw } from 'lucide-react';

src/features/nowPlaying/components/NowPlayingInfo.tsx

@@ -1,6 +1,6 @@
-import { getSongForServer } from '@/api/subsonicLibrary';
+import { getSongForServer } from '@/lib/api/subsonicLibrary';
 import { getArtistInfoForServer } from '@/features/artist';
-import type { SubsonicArtistInfo, SubsonicSong } from '@/api/subsonicTypes';
+import type { SubsonicArtistInfo, SubsonicSong } from '@/lib/api/subsonicTypes';
 import React, { useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { Info } from 'lucide-react';

src/features/nowPlaying/components/TopSongsCard.tsx

@@ -1,7 +1,7 @@
 import React, { memo } from 'react';
 import { useTranslation } from 'react-i18next';
 import { ExternalLink, Play, TrendingUp } from 'lucide-react';
-import type { SubsonicSong } from '@/api/subsonicTypes';
+import type { SubsonicSong } from '@/lib/api/subsonicTypes';
 import { formatTrackTime } from '@/utils/format/formatDuration';
 
 interface TopSongsCardProps {