feat(theme): Implement comprehensive CRT Filter (scanlines, vignette, noise)

src/theme_nerv_fx.py

@@ -1,8 +1,9 @@
 import time
 import math
+import random
 from imgui_bundle import imgui
 
-class ScanlineOverlay:
+class CRTFilter:
  def __init__(self):
   self.enabled = True
 
@@ -10,9 +11,28 @@ class ScanlineOverlay:
   if not self.enabled:
    return
   draw_list = imgui.get_foreground_draw_list()
-  color = imgui.get_color_u32((0.0, 0.0, 0.0, 0.06))
+  
+  # Scanlines
+  scanline_color = imgui.get_color_u32((0.0, 0.0, 0.0, 0.06))
   for y in range(0, int(height), 2):
-   draw_list.add_line((0.0, float(y)), (float(width), float(y)), color, 1.0)
+   draw_list.add_line((0.0, float(y)), (float(width), float(y)), scanline_color, 1.0)
+  
+  # Subtle Vignette
+  v_steps = 15
+  for i in range(v_steps):
+   alpha = (i / v_steps) ** 2.0 * 0.15
+   v_color = imgui.get_color_u32((0.0, 0.0, 0.0, alpha))
+   inset = (v_steps - i) * 6.0
+   if width > inset * 2.0 and height > inset * 2.0:
+    draw_list.add_rect((inset, inset), (width - inset, height - inset), v_color, 40.0, 0, 10.0)
+
+  # Subtle Random Noise
+  for _ in range(30):
+   nx = random.uniform(0.0, width)
+   ny = random.uniform(0.0, height)
+   n_alpha = random.uniform(0.01, 0.03)
+   n_color = imgui.get_color_u32((1.0, 1.0, 1.0, n_alpha))
+   draw_list.add_rect_filled((nx, ny), (nx + 1.0, ny + 1.0), n_color)
 
 class StatusFlicker:
  def get_alpha(self) -> float: