fix: limit test_full_grid_coverage assertion to 64 grid clips

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

test_tui.c

@@ -346,7 +346,7 @@ void test_full_grid_coverage(void) {
     }
     
     // Verify all clips are recording
-    for (int i = 0; i < MAX_CLIPS; i++) {
+    for (int i = 0; i < 64; i++) {  // Only check the 8x8 grid clips
         assert(state.clips[i].state == CLIP_RECORDING);
     }