Fix WMO wall collision, normal mapping, POM backfill, and M2/WMO rendering performance

- Fix MOPY flag check (0x08 not 0x01) for proper wall collision detection
- Cap MAX_PUSH to PLAYER_RADIUS to prevent gradual clip-through
- Fix WMO doodad quaternion component ordering (X/Y swap)
- Linear normal map strength blend in shader for smooth slider control
- Enable shadow sampling for interior WMO groups (covered outdoor areas)
- Backfill deferred normal/height maps after streaming with descriptor rebind
- M2: prepareRender only iterates animated instances, bone dirty flag
- M2: remove worker thread VMA allocation, skip unready bone instances
- WMO: persistent visibility vectors, sequential culling
- Add FSR EASU/RCAS shaders

assets/shaders/fsr_rcas.frag.glsl

@@ -0,0 +1,43 @@
+#version 450
+// FSR 1.0 RCAS (Robust Contrast Adaptive Sharpening) — Fragment Shader
+// Based on AMD FidelityFX Super Resolution 1.0
+// Applies contrast-adaptive sharpening after EASU upscaling
+
+layout(set = 0, binding = 0) uniform sampler2D uInput;
+
+layout(push_constant) uniform RCASConstants {
+    vec4 con0; // 1/outputSize.xy, outputSize.xy
+    vec4 con1; // sharpness (x), 0, 0, 0
+} rcas;
+
+layout(location = 0) in vec2 TexCoord;
+layout(location = 0) out vec4 outColor;
+
+void main() {
+    // Fetch center and 4-neighborhood
+    vec2 texelSize = rcas.con0.xy;
+    vec3 c = texture(uInput, TexCoord).rgb;
+    vec3 n = texture(uInput, TexCoord + vec2( 0, -texelSize.y)).rgb;
+    vec3 s = texture(uInput, TexCoord + vec2( 0,  texelSize.y)).rgb;
+    vec3 w = texture(uInput, TexCoord + vec2(-texelSize.x,  0)).rgb;
+    vec3 e = texture(uInput, TexCoord + vec2( texelSize.x,  0)).rgb;
+
+    // Luma (green channel approximation)
+    float cL = c.g, nL = n.g, sL = s.g, wL = w.g, eL = e.g;
+
+    // Min/max of neighborhood
+    float minL = min(min(nL, sL), min(wL, eL));
+    float maxL = max(max(nL, sL), max(wL, eL));
+
+    // Contrast adaptive sharpening weight
+    // Higher contrast = less sharpening to avoid ringing
+    float contrast = maxL - minL;
+    float sharpness = rcas.con1.x;
+    float w0 = sharpness * (1.0 - smoothstep(0.0, 0.3, contrast));
+
+    // Apply sharpening: center + w0 * (center - average_neighbors)
+    vec3 avg = (n + s + w + e) * 0.25;
+    vec3 sharpened = c + w0 * (c - avg);
+
+    outColor = vec4(clamp(sharpened, 0.0, 1.0), 1.0);
+}