feat: wire up album filtering to photo queue

Album selection now controls which photos are displayed.
Uses POST /api/search/random with albumIds filter (Immich v3
compatible) instead of the removed GET /api/albums/{id} assets.

- Add albumIds parameter to fetchRandomAssets/fetchRandomAssetIds
- syncFromAlbums: fetch random assets filtered by selected albums
- syncFromAllPhotos: preserve existing global random behavior
- Album mode reshuffles on exhaustion instead of re-fetching
- 24h resync checks album assetCounts for changes before re-fetch
- requestSync + albums_changed action triggers queue rebuild on save
- timerWakeCycle respects album selection
- Discard stale pre-renders on album change

Co-authored-by: Cursor <cursoragent@cursor.com>

src/main.cpp

@@ -1,5 +1,6 @@
 #include <Arduino.h>
 #include <M5Unified.h>
+#include <ArduinoJson.h>
 #include <esp_heap_caps.h>
 #include <freertos/FreeRTOS.h>
 #include <freertos/task.h>
@@ -238,9 +239,10 @@ void displayTask(void* param) {
             xSemaphoreGive(stateMutex);
         }
 
-        // Periodic re-sync
+        // Periodic re-sync (includes album change requests)
         if (photoQueue.needsResync() && wifiManager.isConnected()) {
             photoQueue.sync();
+            discardPending(pending);
         }
 
         // --- Phase 1: Display ---
@@ -343,6 +345,9 @@ void webActionCallback(const String& action) {
             slideshowPlaying = false;
         } else if (action == "play") {
             slideshowPlaying = true;
+        } else if (action == "albums_changed") {
+            photoQueue.requestSync();
+            refreshRequested = true;
         }
         xSemaphoreGive(stateMutex);
     }
@@ -368,11 +373,25 @@ void timerWakeCycle() {
     imagePipeline.setBlueNoiseEnabled(s.dither_noise != 0);
     displayManager.setTranslucent(s.meta_translucent != 0);
 
-    // Fetch a small batch of random assets
+    // Fetch assets — respect album selection
     static constexpr int TIMER_WAKE_RETRIES = 5;
     bool displayed = false;
 
-    std::vector<String> ids = immichClient.fetchRandomAssetIds(10);
+    // Parse selected album IDs from settings
+    std::vector<String> albumIds;
+    {
+        JsonDocument doc;
+        DeserializationError err = deserializeJson(doc, s.albums_json);
+        if (!err) {
+            JsonArray arr = doc.as<JsonArray>();
+            for (JsonVariant v : arr) {
+                albumIds.push_back(v.as<String>());
+            }
+        }
+    }
+
+    std::vector<String> ids = immichClient.fetchRandomAssetIds(10, albumIds);
+
     for (int i = 0; i < (int)ids.size() && i < TIMER_WAKE_RETRIES && !displayed; i++) {
         AssetInfo info = immichClient.fetchAssetInfo(ids[i]);