fix: eliminate diagonal dither pattern from display driver

Root cause: Panel_ED2208's epd_quality mode applies _dither_row_rgb_pair
(diagonal bias pattern with dither=140) during _exec_transfer(). Since our
ImagePipeline already does proper Floyd-Steinberg dithering, the driver's
additional dithering was creating visible diagonal artifacts.

Fix: setEpdMode(epd_fastest) selects _dither_row_none (clean nearest-color
lookup, no spatial bias). On Panel_ED2208 this only affects the dither
function — NOT refresh quality or waveform.

Also: default dither_noise setting to OFF since error scatter was targeting
the wrong layer (it made gradient areas fuzzier without fixing the real
problem in the display driver).

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

src/settings.h

@@ -7,7 +7,9 @@ enum class CycleMode : uint8_t {
     Random = 0,
     Chronological = 1,
     ReverseChronological = 2,
-    FavoritesWeighted = 3
+    FavoritesWeighted = 3,
+    WeightedChronological = 4,
+    WeightedReverseChronological = 5
 };
 
 enum class ImageQuality : uint8_t {
@@ -54,8 +56,13 @@ struct Settings {
     String date_fmt;  // strftime-style, default "%Y-%m-%d"
     String time_fmt;  // strftime-style, default "%H:%M:%S"
 
+    // Image pipeline
+    uint8_t pipeline_mode;  // 0=dynamic, 1=balanced, 2=none
+    uint8_t dither_noise;   // 1=blue noise dither smoothing ON, 0=OFF
+
     // Device
     uint8_t led_brightness;
+    uint8_t show_battery;   // 1 = show battery indicator on display
     uint32_t queue_cursor;
     String albums_json;
 };