feat(ui): Improve text rendering clarity with 3x font oversampling

src/bg_shader.py

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+# src/bg_shader.py
+import time
+import math
+from typing import Optional
+import numpy as np
+from imgui_bundle import imgui, nanovg as nvg, hello_imgui
+
+class BackgroundShader:
+ def __init__(self):
+  self.enabled = False
+  self.start_time = time.time()
+  self.ctx: Optional[nvg.Context] = None
+
+ def render(self, width: float, height: float):
+  if not self.enabled:
+   return
+
+  # In imgui-bundle, hello_imgui handles the background.
+  # We can use the background_draw_list to draw primitives.
+  # Since we don't have raw GLSL easily in Python without PyOpenGL,
+  # we'll use a "faux-shader" approach with NanoVG or DrawList gradients.
+  
+  t = time.time() - self.start_time
+  dl = imgui.get_background_draw_list()
+  
+  # Base deep sea color
+  dl.add_rect_filled(imgui.ImVec2(0, 0), imgui.ImVec2(width, height), imgui.get_color_u32(imgui.ImVec4(0.01, 0.07, 0.20, 1.0)))
+  
+  # Layer 1: Slow moving large blobs (FBM approximation)
+  for i in range(3):
+   phase = t * (0.1 + i * 0.05)
+   x = (math.sin(phase) * 0.5 + 0.5) * width
+   y = (math.cos(phase * 0.8) * 0.5 + 0.5) * height
+   radius = (0.4 + 0.2 * math.sin(t * 0.2)) * max(width, height)
+   
+   col = imgui.ImVec4(0.02, 0.26, 0.55, 0.3)
+   dl.add_circle_filled(imgui.ImVec2(x, y), radius, imgui.get_color_u32(col), num_segments=32)
+
+  # Layer 2: Shimmering caustics (Animated Lines)
+  num_lines = 15
+  for i in range(num_lines):
+   offset = (t * 20.0 + i * (width / num_lines)) % width
+   alpha = 0.1 * (1.0 + math.sin(t + i))
+   col = imgui.get_color_u32(imgui.ImVec4(0.08, 0.60, 0.88, alpha))
+   
+   p1 = imgui.ImVec2(offset, 0)
+   p2 = imgui.ImVec2(offset - 100, height)
+   dl.add_line(p1, p2, col, thickness=2.0)
+
+  # Vignette
+  center = imgui.ImVec2(width/2, height/2)
+  radius = max(width, height) * 0.8
+  # Draw multiple concentric circles for a soft vignette
+  for i in range(10):
+   r = radius + (i * 50)
+   alpha = (i / 10.0) * 0.5
+   dl.add_circle(center, r, imgui.get_color_u32(imgui.ImVec4(0, 0, 0, alpha)), num_segments=64, thickness=60.0)
+
+_bg: Optional[BackgroundShader] = None
+
+def get_bg():
+ global _bg
+ if _bg is None:
+  _bg = BackgroundShader()
+ return _bg