feat(m10): file sharing with upload, lightbox, permission, tests, e2e

- FileRepository (CRUD, soft-delete, pagination, project isolation) +
  FileStorageService (local FS save data/uploads/<projectId>/<uuid>.<ext>,
  MIME allowlist, filename sanitize, unique uuid name, member permission,
  file_shared notification to other members, file_uploaded activity log,
  SSE file.uploaded, uploader/admin delete + FS unlink)
- APIs: files list/upload(multipart), download (membership), delete
- Screens: files page + Uploader(multipart) + FileList(image Lightbox,
  PDF link, delete), ProjectNav ファイル link
- Unit tests (FileRepository, FileStorageService) + e2e file-sharing

components/files/FileList.tsx

@@ -0,0 +1,107 @@
+'use client';
+
+import { useState } from 'react';
+import { useRouter } from 'next/navigation';
+import type { FileAsset } from '@/lib/types';
+
+export function FileList({
+  files,
+  canDelete,
+}: {
+  files: FileAsset[];
+  canDelete: boolean;
+}) {
+  const router = useRouter();
+  const [lightbox, setLightbox] = useState<FileAsset | null>(null);
+
+  async function onDelete(fileId: number) {
+    const res = await fetch(`/api/files/${fileId}`, { method: 'DELETE' });
+    if (res.ok) router.refresh();
+  }
+
+  if (files.length === 0) {
+    return <p className="text-sm text-gray-400">ファイルはありません。</p>;
+  }
+
+  return (
+    <>
+      <ul
+        className="grid grid-cols-2 gap-3 sm:grid-cols-3"
+        data-testid="file-list"
+      >
+        {files.map((file) => {
+          const isImage = file.mimeType.startsWith('image/');
+          const isPdf = file.mimeType === 'application/pdf';
+          const url = `/api/files/${file.id}/download`;
+          return (
+            <li
+              key={file.id}
+              className="rounded-lg border bg-white p-3 shadow-sm"
+              data-testid={`file-item-${file.id}`}
+            >
+              {isImage ? (
+                <button
+                  type="button"
+                  onClick={() => setLightbox(file)}
+                  className="block w-full"
+                >
+                  <img
+                    src={url}
+                    alt={file.originalName}
+                    className="h-24 w-full rounded object-cover"
+                  />
+                </button>
+              ) : isPdf ? (
+                <a
+                  href={url}
+                  target="_blank"
+                  rel="noreferrer"
+                  className="flex h-24 items-center justify-center rounded bg-gray-100 text-sm text-blue-600 hover:underline"
+                >
+                  PDF を開く
+                </a>
+              ) : (
+                <a
+                  href={url}
+                  className="flex h-24 items-center justify-center rounded bg-gray-100 text-sm text-blue-600 hover:underline"
+                >
+                  ダウンロード
+                </a>
+              )}
+              <p
+                className="mt-2 truncate text-xs text-gray-700"
+                title={file.originalName}
+              >
+                {file.originalName}
+              </p>
+              <p className="text-xs text-gray-400">{file.size} bytes</p>
+              {canDelete && (
+                <button
+                  type="button"
+                  onClick={() => onDelete(file.id)}
+                  className="mt-1 text-xs text-red-600 hover:underline"
+                >
+                  削除
+                </button>
+              )}
+            </li>
+          );
+        })}
+      </ul>
+
+      {lightbox && (
+        <div
+          className="fixed inset-0 z-50 flex items-center justify-center bg-black/80 p-4"
+          onClick={() => setLightbox(null)}
+          data-testid="lightbox"
+        >
+          <img
+            src={`/api/files/${lightbox.id}/download`}
+            alt={lightbox.originalName}
+            className="max-h-full max-w-full rounded"
+          />
+        </div>
+      )}
+    </>
+  );
+}