feat(P5B.T4): TicTacToeBoard + ConnectFourBoard render-only components

apps/desktop/src/components/ConnectFourBoard.tsx

@@ -0,0 +1,61 @@
+import {
+  C4_COLS,
+  C4_ROWS,
+  c4DropRow,
+  c4WinningCells,
+  type Cell,
+} from '@chat-app/shared/chat';
+
+interface Props {
+  board: Cell[];
+  myPlayerIdx: 0 | 1 | null;
+  disabled: boolean;
+  onMove: (column: number) => void;
+}
+
+export function ConnectFourBoard({ board, myPlayerIdx, disabled, onMove }: Props) {
+  const winCells = c4WinningCells(board);
+  const winSet = new Set<number>(winCells ?? []);
+
+  return (
+    <div
+      className="mx-auto w-full max-w-2xl rounded-2xl bg-sky-900/40 p-3"
+      role="grid"
+      aria-label="Vier-Gewinnt"
+    >
+      <div
+        className="grid gap-1.5"
+        style={{ gridTemplateColumns: 'repeat(' + C4_COLS + ', minmax(0, 1fr))' }}
+      >
+        {Array.from({ length: C4_ROWS * C4_COLS }, (_, idx) => {
+          const cell = board[idx];
+          const col = idx % C4_COLS;
+          const dropTo = c4DropRow(board, col);
+          const canClickColumn = !disabled && dropTo >= 0 && myPlayerIdx !== null;
+          const inWin = winSet.has(idx);
+          return (
+            <button
+              key={idx}
+              type="button"
+              onClick={() => canClickColumn && onMove(col)}
+              disabled={!canClickColumn}
+              aria-label={'Spalte ' + (col + 1) + (cell !== null ? ' belegt' : '')}
+              className={
+                'flex aspect-square items-center justify-center rounded-full border-2 transition ' +
+                (inWin
+                  ? 'border-emerald-300 bg-emerald-400 shadow-[0_0_12px_rgba(110,231,183,0.7)]'
+                  : cell === 0
+                    ? 'border-rose-300 bg-rose-500'
+                    : cell === 1
+                      ? 'border-amber-300 bg-amber-400'
+                      : canClickColumn
+                        ? 'cursor-pointer border-sky-700 bg-sky-950 hover:bg-sky-900'
+                        : 'cursor-not-allowed border-sky-800 bg-sky-950 opacity-80')
+              }
+            />
+          );
+        })}
+      </div>
+    </div>
+  );
+}

apps/desktop/src/components/TicTacToeBoard.tsx

@@ -0,0 +1,53 @@
+import { type Cell, tttWinningLine } from '@chat-app/shared/chat';
+
+interface Props {
+  board: Cell[];
+  myPlayerIdx: 0 | 1 | null;
+  disabled: boolean;
+  onMove: (cell: number) => void;
+}
+
+const MARK = ['×', '○'] as const;
+
+export function TicTacToeBoard({ board, myPlayerIdx, disabled, onMove }: Props) {
+  const winLine = tttWinningLine(board);
+  const winSet = new Set<number>(winLine ?? []);
+
+  return (
+    <div
+      className="mx-auto grid w-full max-w-md grid-cols-3 gap-2 p-4"
+      style={{ aspectRatio: '1 / 1' }}
+      role="grid"
+      aria-label="Tic-Tac-Toe"
+    >
+      {board.map((cell, i) => {
+        const filled = cell !== null;
+        const inWin = winSet.has(i);
+        const canClick = !disabled && !filled && myPlayerIdx !== null;
+        return (
+          <button
+            key={i}
+            type="button"
+            onClick={() => canClick && onMove(i)}
+            disabled={!canClick}
+            aria-label={'Feld ' + (i + 1) + (filled ? ' belegt' : ' frei')}
+            className={
+              'flex aspect-square items-center justify-center rounded-xl border-2 text-5xl font-bold transition ' +
+              (inWin
+                ? 'border-emerald-400 bg-emerald-400/20 text-emerald-200'
+                : filled
+                  ? cell === 0
+                    ? 'border-rose-500/60 bg-rose-500/10 text-rose-300'
+                    : 'border-sky-500/60 bg-sky-500/10 text-sky-300'
+                  : canClick
+                    ? 'cursor-pointer border-line bg-surface-2 text-fg-muted hover:bg-surface-3 hover:text-fg'
+                    : 'cursor-not-allowed border-line bg-surface-2 text-fg-muted opacity-60')
+            }
+          >
+            {filled ? MARK[cell as 0 | 1] : ''}
+          </button>
+        );
+      })}
+    </div>
+  );
+}