refactor: simplify Plane/Widget usage

src/tui/tui.zig

@@ -1037,10 +1037,22 @@ pub fn resize(self: *Self) void {
     need_render();
 }
 
-pub fn stdplane(self: *Self) renderer.Plane {
+pub fn plane() renderer.Plane {
+    return current().rdr.stdplane();
+}
+
+fn stdplane(self: *Self) renderer.Plane {
     return self.rdr.stdplane();
 }
 
+pub fn egc_chunk_width(chunk: []const u8, abs_col: usize, tab_width: usize) usize {
+    return plane().egc_chunk_width(chunk, abs_col, tab_width);
+}
+
+pub fn egc_last(egcs: []const u8) []const u8 {
+    return plane().egc_last(egcs);
+}
+
 pub fn screen(self: *Self) Widget.Box {
     return Widget.Box.from(self.rdr.stdplane());
 }