Reorganize into role-based folders and consolidate art

Move every script and scene into role-based directories (actors/, systems/, ui/,
levels/, props/) and all raw art under art/ (grouped by role, snake_case,
Extract-Textures GLBs), dropping Blender version-suffix noise. Filenames are
snake_case (PascalCase reserved for class_name) to avoid case-insensitive
filesystem aliasing on the web/macOS targets. Routes the bull's hits through the
typed DamageEvent pipeline and wires the bull's abilities to the Fx library.
Updates CLAUDE.md's folder-layout overview to match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CCyaJPTHCH9EDthpf4A5Sj

ui/menu_blur.gdshader

@@ -0,0 +1,25 @@
+shader_type canvas_item;
+
+// Blurred, darkened backdrop for the intro video. A COVER-scaled copy of the
+// clip sits behind the sharp fitted clip so portrait/ultrawide screens fill
+// edge-to-edge instead of showing dead bars.
+
+uniform float blur_radius : hint_range(0.0, 8.0) = 3.0;
+uniform float darken : hint_range(0.0, 1.0) = 0.35;
+
+void fragment() {
+	vec2 px = TEXTURE_PIXEL_SIZE * blur_radius;
+	vec4 sum = vec4(0.0);
+	// 3x3 gaussian-ish tap, weights sum to 16.
+	sum += texture(TEXTURE, UV + vec2(-px.x, -px.y)) * 1.0;
+	sum += texture(TEXTURE, UV + vec2(0.0,   -px.y)) * 2.0;
+	sum += texture(TEXTURE, UV + vec2(px.x,  -px.y)) * 1.0;
+	sum += texture(TEXTURE, UV + vec2(-px.x,  0.0))  * 2.0;
+	sum += texture(TEXTURE, UV)                      * 4.0;
+	sum += texture(TEXTURE, UV + vec2(px.x,   0.0))  * 2.0;
+	sum += texture(TEXTURE, UV + vec2(-px.x,  px.y)) * 1.0;
+	sum += texture(TEXTURE, UV + vec2(0.0,    px.y)) * 2.0;
+	sum += texture(TEXTURE, UV + vec2(px.x,   px.y)) * 1.0;
+	sum /= 16.0;
+	COLOR = vec4(sum.rgb * (1.0 - darken), sum.a);
+}