fix(addon-fit): remove redundant same-dimension guard in fit()

Terminal.resize() already no-ops internally when dimensions haven't
changed. The addon's guard prevented resize() from being called at all,
forcing callers using ResizeObserver-based layouts to use perturbation
workarounds (resize to rows-1, then fit) that race with the observer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

addons/addon-fit/src/FitAddon.ts

@@ -48,10 +48,7 @@ export class FitAddon implements ITerminalAddon, IFitApi {
       return;
     }
 
-    // Force a full render
-    if (this._terminal.rows !== dims.rows || this._terminal.cols !== dims.cols) {
-      this._terminal.resize(dims.cols, dims.rows);
-    }
+    this._terminal.resize(dims.cols, dims.rows);
   }
 
   public proposeDimensions(): ITerminalDimensions | undefined {