feat: expand multiplayer, chat, and release support

- add network NPC synchronization and dialogue interactions
- add world bulletin publishing and display
- improve authentication, session refresh, and appearance sync
- synchronize player direction and movement animations
- improve input focus and progressive Web loading
- add macOS/Windows builds and deployment configuration
- include required fonts, shaders, and runtime assets

assets/shaders/avatar_round_mask.gdshader

@@ -0,0 +1,15 @@
+shader_type canvas_item;
+
+uniform float corner_radius = 0.22;
+uniform float edge_feather = 0.008;
+
+void fragment() {
+	vec2 q = abs(UV - vec2(0.5)) - (vec2(0.5) - vec2(corner_radius));
+	float outside_distance = length(max(q, vec2(0.0)));
+	float inside_distance = min(max(q.x, q.y), 0.0);
+	float signed_distance = outside_distance + inside_distance - corner_radius;
+	float mask = 1.0 - smoothstep(0.0, edge_feather, signed_distance);
+
+	COLOR = texture(TEXTURE, UV);
+	COLOR.a *= mask;
+}