feat(music): mini player ekle

Müzik çalar durumunu yönetmek için global store oluştur.
Özel bir mini player bileşeni ile çalma listesi ve kontrolleri ekle.
Müzik çaların uygulama genelinde kalıcı olmasını sağla.

client/src/stores/musicPlayerStore.js

@@ -0,0 +1,203 @@
+import { writable, get } from "svelte/store";
+import { API, withToken } from "../utils/api.js";
+
+const INITIAL_STATE = {
+  currentTrack: null,
+  currentIndex: -1,
+  queue: [],
+  isPlaying: false,
+  currentTime: 0,
+  duration: 0,
+  volume: 0.8,
+  isMuted: false
+};
+
+const { subscribe, set, update } = writable({ ...INITIAL_STATE });
+
+let audio = null;
+let previousVolume = INITIAL_STATE.volume;
+
+function ensureAudio() {
+  if (audio || typeof Audio === "undefined") return;
+  audio = new Audio();
+  audio.preload = "metadata";
+  audio.volume = INITIAL_STATE.volume;
+
+  audio.addEventListener("timeupdate", () => {
+    update((state) => ({
+      ...state,
+      currentTime: audio.currentTime || 0,
+      duration: Number.isFinite(audio.duration) ? audio.duration : state.duration
+    }));
+  });
+
+  audio.addEventListener("loadedmetadata", () => {
+    update((state) => ({
+      ...state,
+      duration: Number.isFinite(audio.duration) ? audio.duration : 0
+    }));
+  });
+
+  audio.addEventListener("play", () => {
+    update((state) => ({ ...state, isPlaying: true }));
+  });
+
+  audio.addEventListener("pause", () => {
+    update((state) => ({ ...state, isPlaying: false }));
+  });
+
+  audio.addEventListener("ended", () => {
+    playNext();
+  });
+}
+
+function buildStreamURL(item) {
+  const base = `${API}/stream/${item.infoHash}?index=${item.fileIndex || 0}`;
+  return withToken(base);
+}
+
+function setQueue(items = []) {
+  update((state) => ({ ...state, queue: Array.isArray(items) ? items : [] }));
+}
+
+function playTrack(item, index, items = null) {
+  if (!item) return;
+  ensureAudio();
+  if (items) setQueue(items);
+  const state = get({ subscribe });
+  const nextIndex =
+    Number.isFinite(index) && index >= 0
+      ? index
+      : state.queue.findIndex((entry) => entry.id === item.id);
+
+  update((prev) => ({
+    ...prev,
+    currentTrack: item,
+    currentIndex: nextIndex,
+    currentTime: 0,
+    duration: item.mediaInfo?.format?.duration || 0
+  }));
+
+  if (!audio) return;
+  audio.src = buildStreamURL(item);
+  audio
+    .play()
+    .catch(() => update((prev) => ({ ...prev, isPlaying: false })));
+}
+
+function playByIndex(index) {
+  ensureAudio();
+  const state = get({ subscribe });
+  if (!state.queue.length || index < 0 || index >= state.queue.length) return;
+  const item = state.queue[index];
+  update((prev) => ({
+    ...prev,
+    currentTrack: item,
+    currentIndex: index,
+    currentTime: 0,
+    duration: item.mediaInfo?.format?.duration || 0
+  }));
+  if (!audio) return;
+  audio.src = buildStreamURL(item);
+  audio
+    .play()
+    .catch(() => update((prev) => ({ ...prev, isPlaying: false })));
+}
+
+function togglePlay() {
+  ensureAudio();
+  const state = get({ subscribe });
+  if (!audio || !state.currentTrack) return;
+  if (state.isPlaying) {
+    audio.pause();
+  } else {
+    audio
+      .play()
+      .catch(() => update((prev) => ({ ...prev, isPlaying: false })));
+  }
+}
+
+function playNext() {
+  const state = get({ subscribe });
+  if (!state.queue.length) return;
+  const nextIndex =
+    state.currentIndex >= 0
+      ? (state.currentIndex + 1) % state.queue.length
+      : 0;
+  playByIndex(nextIndex);
+}
+
+function playPrevious() {
+  const state = get({ subscribe });
+  if (!state.queue.length) return;
+  const prevIndex =
+    state.currentIndex > 0
+      ? state.currentIndex - 1
+      : state.queue.length - 1;
+  playByIndex(prevIndex);
+}
+
+function seekToPercent(percent) {
+  ensureAudio();
+  if (!audio) return;
+  const state = get({ subscribe });
+  if (!state.duration) return;
+  const nextTime = (Number(percent) / 100) * state.duration;
+  audio.currentTime = nextTime;
+  update((prev) => ({ ...prev, currentTime: nextTime }));
+}
+
+function setVolume(value) {
+  ensureAudio();
+  const volume = Math.min(Math.max(Number(value) || 0, 0), 1);
+  if (audio) audio.volume = volume;
+  update((prev) => ({
+    ...prev,
+    volume,
+    isMuted: volume === 0
+  }));
+}
+
+function toggleMute() {
+  ensureAudio();
+  const state = get({ subscribe });
+  if (!audio) return;
+  if (state.isMuted || state.volume === 0) {
+    const nextVolume = previousVolume || 0.8;
+    audio.volume = nextVolume;
+    update((prev) => ({
+      ...prev,
+      volume: nextVolume,
+      isMuted: false
+    }));
+  } else {
+    previousVolume = state.volume;
+    audio.volume = 0;
+    update((prev) => ({
+      ...prev,
+      volume: 0,
+      isMuted: true
+    }));
+  }
+}
+
+function stopPlayback() {
+  if (audio) {
+    audio.pause();
+    audio.src = "";
+  }
+  set({ ...INITIAL_STATE });
+}
+
+export const musicPlayer = { subscribe };
+export {
+  setQueue,
+  playTrack,
+  togglePlay,
+  playNext,
+  playPrevious,
+  seekToPercent,
+  setVolume,
+  toggleMute,
+  stopPlayback
+};