Increase VectorEngine timeouts and add image UI

Add VectorEngine image generation config and raise request timeouts (env + scripts) from 180000 to 1000000ms. Introduce a reusable CreativeImageInputPanel component with tests and wire up mobile keyboard-focus helpers; update generation views and related tests (CustomWorldGenerationView, BarkBattle editor, Match3D, Puzzle flows). Improve API error handling / VectorEngine request guidance (packages/shared http.ts and docs), and apply multiple backend/frontend fixes for puzzle/match3d/prompt handling. Also include extensive docs and decision-log updates describing UI/UX decisions and verification steps.

src/components/puzzle-runtime/PuzzleRuntimeShell.tsx

@@ -1329,7 +1329,8 @@ export function PuzzleRuntimeShell({
               const piece = pieceByCell.get(`${cell.row}:${cell.col}`) ?? null;
               const occupied = Boolean(piece);
               const isMerged = mergedCellKeys.has(boardCellKey(cell));
-              const isSelected = piece?.pieceId === selectedPieceId;
+              const isSelected =
+                !isMerged && piece?.pieceId === selectedPieceId;
 
               return (
                 <div