fix(style): Z-Design V4 - El rojo es el estándar, boost para azul

Corrección de rumbo consensuada:
- Colores brillantes (L > 0.2): 22% intensidad (estándar del rojo)
- Colores oscuros (L <= 0.2): 35% intensidad (boost para azul/violeta)

El objetivo es que todos los paneles tengan la vibrancia del rojo.
El azul debe 'saltar' del negro tanto como lo hace el rojo.

src/core/style.zig

@@ -1373,27 +1373,32 @@ pub const DerivedPanelColors = struct {
     title_color: Color,
 };
 
-/// Derive panel frame colors from a single base color using generic luminance formula.
+/// Derive panel frame colors from a single base color.
 ///
-/// The derivation is purely mathematical and works for ANY color:
-/// - Luminance L = 0.2126*R + 0.7152*G + 0.0722*B
-/// - Blend factor inversely proportional to L
+/// Z-Design V4: "El rojo es el estándar"
+/// - Colores brillantes (L > 0.2, ej: rojo): 22% color visible (el estándar bueno)
+/// - Colores oscuros (L <= 0.2, ej: azul): 35% color visible (boost para compensar)
 ///
-/// Example values:
-/// - Blue (L=0.07): blend ~19% → more blue visible in dark background
-/// - Red (L=0.21): blend ~18% → moderate visibility
-/// - Green (L=0.72): blend ~13% → less green (already bright)
-/// - Yellow (L=0.93): blend ~11% → minimal (very bright)
+/// El objetivo es que TODOS los paneles tengan la vibrancia del rojo.
+/// El azul debe "saltar" del negro tanto como lo hace el rojo.
+///
+/// Luminance L = 0.2126*R + 0.7152*G + 0.0722*B
+/// - Rojo puro: L ~= 0.21 (justo en el límite, usa estándar 22%)
+/// - Azul puro: L ~= 0.07 (muy bajo, usa boost 35%)
+/// - Verde puro: L ~= 0.72 (alto, usa estándar 22%)
 pub fn derivePanelFrameColors(base: Color) DerivedPanelColors {
     const L = base.perceptualLuminance();
 
-    // Generic formula: blend inversely proportional to luminance
-    // Base blend: 10% (bright colors), Max blend: 20% (dark colors)
-    const base_blend: f32 = 0.10;
-    const max_blend: f32 = 0.20;
-    const blend_factor = base_blend + (max_blend - base_blend) * (1.0 - L);
+    // Z-Design V4: Threshold-based boost
+    // El rojo (~22%) es el estándar de "buena vibrancia"
+    // Colores oscuros como el azul necesitan más intensidad para verse igual
+    const blend_factor: f32 = if (L > 0.2)
+        0.22 // Estándar: colores brillantes (rojo, verde, amarillo)
+    else
+        0.35; // Boost: colores oscuros (azul, violeta)
 
     // Convert to percentage for blendTowards (inverted: 100% = all black)
+    // focus: full blend, unfocus: half blend
     const focus_pct: u8 = @intFromFloat((1.0 - blend_factor) * 100.0);
     const unfocus_pct: u8 = @intFromFloat((1.0 - blend_factor * 0.5) * 100.0);
 
@@ -1408,35 +1413,44 @@ pub fn derivePanelFrameColors(base: Color) DerivedPanelColors {
     };
 }
 
-test "derivePanelFrameColors blue" {
-    const blue = Color.rgb(59, 130, 246); // laravel_blue
+test "derivePanelFrameColors blue gets boost" {
+    // Pure blue has L ~= 0.07, which is < 0.2, so it gets 35% boost
+    const blue = Color.rgb(0, 0, 255);
     const derived = derivePanelFrameColors(blue);
 
-    // Blue has low luminance, should get more visible background
-    // L ~= 0.07 * 0.23 + 0.51 * 0.72 + 0.96 * 0.07 = 0.016 + 0.37 + 0.067 = 0.45
-    // Actually for laravel_blue: L = 59/255*0.2126 + 130/255*0.7152 + 246/255*0.0722
-    //                          = 0.049 + 0.365 + 0.070 = 0.484
-
     // Border focus should be the original color
     try std.testing.expectEqual(blue.r, derived.border_focus.r);
     try std.testing.expectEqual(blue.g, derived.border_focus.g);
     try std.testing.expectEqual(blue.b, derived.border_focus.b);
 
-    // Focus bg should be darker than unfocus bg (more blend towards black)
-    // Actually focus has MORE color (less blend to black)
-    try std.testing.expect(derived.focus_bg.r >= derived.unfocus_bg.r);
+    // Focus bg should have significant blue visible (35% boost)
+    // 35% of 255 = ~89, blended with soft_black (17,17,20)
+    try std.testing.expect(derived.focus_bg.b > 70); // Should be vibrant blue
 }
 
-test "derivePanelFrameColors generic formula" {
-    // Test that brighter colors get less visibility (lower blend)
-    const dark_blue = Color.rgb(0, 0, 200); // L ~= 0.057
-    const bright_yellow = Color.rgb(255, 255, 0); // L ~= 0.93
+test "derivePanelFrameColors red is standard" {
+    // Red has L ~= 0.21, which is > 0.2, so it gets standard 22%
+    const red = Color.rgb(255, 0, 0);
+    const derived = derivePanelFrameColors(red);
 
-    const blue_derived = derivePanelFrameColors(dark_blue);
-    const yellow_derived = derivePanelFrameColors(bright_yellow);
-
-    // Blue background should have more color visible (less black blend)
-    // This means blue's focus_bg should be brighter/more colorful than yellow's relative to base
-    // We check that the formula produces different results
-    try std.testing.expect(blue_derived.focus_bg.b != yellow_derived.focus_bg.b);
+    // Focus bg should have standard red visibility (22%)
+    // 22% of 255 = ~56, blended with soft_black
+    try std.testing.expect(derived.focus_bg.r > 40);
+    try std.testing.expect(derived.focus_bg.r < 100); // Not too bright
+}
+
+test "derivePanelFrameColors threshold behavior" {
+    // Test that blue (L < 0.2) gets MORE visibility than red (L > 0.2)
+    const blue = Color.rgb(0, 0, 255); // L ~= 0.07
+    const red = Color.rgb(255, 0, 0);  // L ~= 0.21
+
+    const blue_derived = derivePanelFrameColors(blue);
+    const red_derived = derivePanelFrameColors(red);
+
+    // Blue gets 35% blend, red gets 22%
+    // So blue's color channel should be proportionally MORE visible
+    // Blue: 35% of 255 ~= 89
+    // Red: 22% of 255 ~= 56
+    // Blue should have higher relative intensity
+    try std.testing.expect(blue_derived.focus_bg.b > red_derived.focus_bg.r);
 }