OTA: quiet the audio sources during a firmware upload

An upload during an active Spotify session crawled (~10 kB/s, 197 s)
and ended in a reset (seen twice). Workaround:
- aes67_ota_on_update(cb): cb(true) right before an accepted upload
  writes flash, cb(false) if it then fails.
- The player pauses Spotify (spotify_pause -> SpircHandler::setPause, the
  app follows) and suspends HLS fetching (hls_suspend); resumed if the
  upload fails. AES67 TX keeps running (silence).
- Verified: upload during Spotify playback paused the session and
  installed in 25.8 s (normal for 2 MB), clean reboot and self-test.
  Root cause still open (noted in CLAUDE.md with the other cspot items).

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

components/spotify/include/spotify.h

@@ -1,6 +1,7 @@
 // Spotify Connect (cspot). Project code; GPL-3.0 through cspot.
 #pragma once
 
+#include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -24,6 +25,8 @@ typedef void (*spotify_event_cb_t)(spotify_event_t ev, int value);
 // Registers the zeroconf endpoints (/spotify_info) and, when source.mode is spotify/auto and the
 // client credentials are set, advertises the device and starts the session task.
 esp_err_t spotify_init(spotify_pcm_cb_t pcm, spotify_event_cb_t event);
+// Pause/resume the running session (the Spotify app follows). No-op without a session.
+void spotify_pause(bool pause);
 // Current state for status.spotify_state.
 const char *spotify_state(void);
 

components/spotify/spotify.cpp

@@ -30,9 +30,19 @@ static std::shared_ptr<cspot::LoginBlob> s_blob;
 static std::atomic<bool> s_got_blob{false};
 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_pause(bool pause)
+{
+    auto h = s_handler;
+    if (h) {
+        h->setPause(pause);
+        ESP_LOGI(TAG, "%s", pause ? "paused" : "resumed");
+    }
+}
+
 const char *spotify_state(void)
 {
     return s_state.load();
@@ -225,6 +235,7 @@ static void session(void)
         }
         ESP_LOGI(TAG, "event %s", event_name(ev->eventType));
     });
+    s_handler = handler;
     s_state = "connected";
     ESP_LOGI(TAG, "connected as %s", ctx->config.username.c_str());
     while (true) {
@@ -246,6 +257,7 @@ static void spotify_task(void *arg)
             s_state = "error";
             ESP_LOGE(TAG, "session ended: %s", e.what());
         }
+        s_handler.reset();
         vTaskDelay(pdMS_TO_TICKS(2000));
     }
 }