fix: UI polish — notification history buttons, CSS test error handling, schedule time picker, empty state labels

- Notification history: replace text buttons with icon buttons, use modal-footer for proper positioning
- CSS test: reject 0-LED picture sources with clear error message, show WS close reason in UI
- Calibration: distribute LEDs by aspect ratio (16:9 default) instead of evenly across edges
- Value source schedule: replace native time input with custom HH:MM picker matching automation style
- Remove "No ... yet" empty state labels from all CardSection instances

server/src/wled_controller/core/capture/calibration.py

@@ -668,14 +668,20 @@ def create_pixel_mapper(
     return PixelMapper(calibration, interpolation_mode)
 
 
-def create_default_calibration(led_count: int) -> CalibrationConfig:
+def create_default_calibration(
+    led_count: int,
+    aspect_width: int = 16,
+    aspect_height: int = 9,
+) -> CalibrationConfig:
     """Create a default calibration for a rectangular screen.
 
-    Assumes LEDs are evenly distributed around the screen edges in clockwise order
-    starting from bottom-left.
+    Distributes LEDs proportionally to the screen aspect ratio so that
+    horizontal and vertical edges have equal LED density.
 
     Args:
         led_count: Total number of LEDs
+        aspect_width: Screen width component of the aspect ratio (default 16)
+        aspect_height: Screen height component of the aspect ratio (default 9)
 
     Returns:
         Default calibration configuration
@@ -683,15 +689,48 @@ def create_default_calibration(led_count: int) -> CalibrationConfig:
     if led_count < 4:
         raise ValueError("Need at least 4 LEDs for default calibration")
 
-    # Distribute LEDs evenly across 4 edges
-    leds_per_edge = led_count // 4
-    remainder = led_count % 4
+    # Distribute LEDs proportionally to aspect ratio (same density per edge)
+    perimeter = 2 * (aspect_width + aspect_height)
+    h_frac = aspect_width / perimeter   # fraction for each horizontal edge
+    v_frac = aspect_height / perimeter  # fraction for each vertical edge
 
-    # Distribute remainder to longer edges (bottom and top)
-    bottom_count = leds_per_edge + (1 if remainder > 0 else 0)
-    right_count = leds_per_edge
-    top_count = leds_per_edge + (1 if remainder > 1 else 0)
-    left_count = leds_per_edge + (1 if remainder > 2 else 0)
+    # Float counts, then round so total == led_count
+    raw_h = led_count * h_frac
+    raw_v = led_count * v_frac
+    bottom_count = round(raw_h)
+    top_count = round(raw_h)
+    right_count = round(raw_v)
+    left_count = round(raw_v)
+
+    # Fix rounding error
+    diff = led_count - (bottom_count + top_count + right_count + left_count)
+    # Distribute remainder to horizontal edges first (longer edges)
+    if diff > 0:
+        bottom_count += 1
+        diff -= 1
+    if diff > 0:
+        top_count += 1
+        diff -= 1
+    if diff > 0:
+        right_count += 1
+        diff -= 1
+    if diff > 0:
+        left_count += 1
+        diff -= 1
+    # If we over-counted, remove from shorter edges first
+    if diff < 0:
+        left_count += diff  # diff is negative
+        diff = 0
+    if left_count < 0:
+        diff = left_count
+        left_count = 0
+        right_count += diff
+
+    # Ensure each edge has at least 1 LED
+    bottom_count = max(1, bottom_count)
+    top_count = max(1, top_count)
+    right_count = max(1, right_count)
+    left_count = max(1, left_count)
 
     config = CalibrationConfig(
         layout="clockwise",
@@ -703,7 +742,8 @@ def create_default_calibration(led_count: int) -> CalibrationConfig:
     )
 
     logger.info(
-        f"Created default calibration for {led_count} LEDs: "
+        f"Created default calibration for {led_count} LEDs "
+        f"(aspect {aspect_width}:{aspect_height}): "
         f"bottom={bottom_count}, right={right_count}, "
         f"top={top_count}, left={left_count}"
     )