Improve player and foliage shadow quality and stability

- ensure player transform sync is not gated by third-person so player shadow stays consistent

- hold shadow projection center during movement and snap once on stop to remove delayed catch-up

- smooth foliage caster transitions using blended phase-shifted UV samples

- tune foliage motion frequencies/amplitudes for less popping

- increase shadow map resolution to 2048 and retune terrain PCF texel scale

- increase global shadow strength from 0.62 to 0.68 for stronger, clearer shadows

assets/shaders/terrain.frag

@@ -53,7 +53,7 @@ float calcShadow() {
     vec3 lightDir = normalize(-uLightDir);
     float bias = max(0.005 * (1.0 - dot(norm, lightDir)), 0.001);
     // 5-tap PCF tuned for slightly sharper detail while keeping stability.
-    vec2 texel = vec2(1.0 / 1536.0);
+    vec2 texel = vec2(1.0 / 2048.0);
     float ref = proj.z - bias;
     vec2 off = texel * 0.7;
     float shadow = 0.0;