Re-added files that were corrupted

Renders/Office/Monitor/alpha_transparency.gdshader

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+shader_type canvas_item;
+
+// Parameters
+uniform float alpha_threshold : hint_range(0.0, 1.0) = 0.1; // below this = fully transparent
+uniform float alpha_modifier  : hint_range(0.0, 1.0) = 1.0; // global alpha multiplier
+
+void fragment() {
+    // Sample the texture
+    vec4 tex_color = texture(TEXTURE, UV);
+
+    // Use the texture's alpha channel directly
+    float alpha = tex_color.a < alpha_threshold ? 0.0 : tex_color.a;
+
+    // Apply global modifier
+    alpha *= alpha_modifier;
+
+    // Preserve original RGB, apply computed alpha
+    COLOR = vec4(tex_color.rgb, alpha);
+}