Spotify: end the session for OTA; app volume starts at the player's

- OTA: the player now ends the Spotify session (spotify_suspend: stop
  flag, waits until the session's tasks are gone, refuses new ones)
  instead of pausing it, and suspends HLS. Pausing was not enough (an
  upload still failed once with a paused session). Verified twice with a
  session running for minutes: "Disconnecting mercury session / session
  ended / suspended", installed in ~26 s, clean reboot.
- Volume: createFromBlob() starts cspot at volume 0, which the app
  showed while we played at 100 %. The session now starts with the
  player's volume (spotify_set_volume); volumes coming from the app are
  stored exactly, without echo. Verified: slider starts at 100 %.

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

components/spotify/spotify.cpp

@@ -33,12 +33,44 @@ static std::string s_name;                              // advertised device nam
 static std::atomic<bool> s_enabled{false};
 static std::atomic<bool> s_stop{false};                 // end the running session
 static std::atomic<bool> s_got_blob{false};
+static std::atomic<bool> s_in_session{false};           // session() running (its tasks may exist)
+static std::atomic<int> s_volume{65535};                // player volume in Spotify units (0..65535)
 static std::atomic<const char *> s_state{"disabled"};
 static std::atomic<uint64_t> s_pcm_bytes{0};
 static std::shared_ptr<cspot::SpircHandler> s_handler;    // running session, else null
 static spotify_pcm_cb_t s_pcm_cb;
 static spotify_event_cb_t s_event_cb;
 
+extern "C" void spotify_suspend(bool suspend)
+{
+    if (!suspend) {
+        spotify_apply();
+        return;
+    }
+    s_enabled = false;
+    s_stop = true;
+    s_got_blob = false;
+    s_state = "suspended";
+    for (int i = 0; i < 30 && s_in_session; i++) {  // session loop exits within 200 ms, then disconnect
+        vTaskDelay(pdMS_TO_TICKS(100));
+    }
+    ESP_LOGI(TAG, "suspended%s", s_in_session ? " (session still ending)" : "");
+}
+
+extern "C" void spotify_set_volume(int pct)
+{
+    pct = pct < 0 ? 0 : pct > 100 ? 100 : pct;
+    int v = pct * 65535 / 100;
+    if (v == s_volume) {
+        return;
+    }
+    s_volume = v;
+    auto h = s_handler;
+    if (h) {
+        h->setRemoteVolume(v);
+    }
+}
+
 extern "C" void spotify_pause(bool pause)
 {
     auto h = s_handler;
@@ -203,6 +235,8 @@ static void session(void)
     ctx->config.clientSecret = client_secret;
     ctx->config.audioFormat = bitrate >= 320 ? AudioFormat_OGG_VORBIS_320
                               : bitrate >= 160 ? AudioFormat_OGG_VORBIS_160 : AudioFormat_OGG_VORBIS_96;
+    // createFromBlob() starts at volume 0, which the app would show; report what we actually play.
+    ctx->config.volume = s_volume;
     s_state = "connecting";
     ctx->session->connectWithRandomAp();
     auto token = ctx->session->authenticate(login);
@@ -246,6 +280,7 @@ static void session(void)
             }
             break;
         case E::VOLUME:
+            s_volume = std::get<int>(ev->data);     // exact value from the app, no echo back
             if (s_event_cb) {
                 s_event_cb(SPOTIFY_EV_VOLUME, std::get<int>(ev->data));
             }
@@ -278,6 +313,7 @@ static void spotify_task(void *arg)
         }
         s_got_blob = false;
         s_stop = false;
+        s_in_session = true;
         try {
             session();
         } catch (const std::exception &e) {
@@ -285,6 +321,7 @@ static void spotify_task(void *arg)
             ESP_LOGE(TAG, "session ended: %s", e.what());
         }
         s_handler.reset();
+        s_in_session = false;
         vTaskDelay(pdMS_TO_TICKS(2000));
     }
 }