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>
+      )}
+    </>
+  );
+}

components/files/Uploader.tsx

@@ -0,0 +1,58 @@
+'use client';
+
+import { useRef, useState } from 'react';
+import { useRouter } from 'next/navigation';
+
+export function Uploader({ projectId }: { projectId: number }) {
+  const router = useRouter();
+  const inputRef = useRef<HTMLInputElement>(null);
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  async function onFile(event: React.ChangeEvent<HTMLInputElement>) {
+    const file = event.target.files?.[0];
+    if (!file) return;
+    setLoading(true);
+    setError(null);
+    const form = new FormData();
+    form.append('file', file);
+    const res = await fetch(`/api/projects/${projectId}/files`, {
+      method: 'POST',
+      body: form,
+    });
+    setLoading(false);
+    if (res.ok) {
+      if (inputRef.current) inputRef.current.value = '';
+      router.refresh();
+    } else {
+      const b = (await res.json().catch(() => null)) as {
+        error?: { message?: string };
+      } | null;
+      setError(b?.error?.message ?? 'アップロードに失敗しました');
+    }
+  }
+
+  return (
+    <div className="rounded-lg border bg-white p-4 shadow-sm">
+      <label className="block text-sm font-medium">
+        ファイルをアップロード
+      </label>
+      <input
+        ref={inputRef}
+        type="file"
+        onChange={onFile}
+        disabled={loading}
+        className="mt-2 block text-sm"
+        data-testid="file-input"
+      />
+      {loading && (
+        <p className="mt-1 text-sm text-gray-500">アップロード中...</p>
+      )}
+      {error && (
+        <p className="mt-1 text-sm text-red-600" role="alert">
+          {error}
+        </p>
+      )}
+    </div>
+  );
+}

components/layout/ProjectNav.tsx

@@ -4,6 +4,7 @@ const NAV_ITEMS = [
   { href: '/notes', label: 'メモ' },
   { href: '/chat', label: 'チャット' },
   { href: '/todos', label: 'ToDo' },
+  { href: '/files', label: 'ファイル' },
   { href: '/members', label: 'メンバー' },
   { href: '/activity', label: 'アクティビティ' },
   { href: '/settings', label: '設定' },
@@ -24,6 +25,7 @@ export function ProjectNav({
     | 'notes'
     | 'chat'
     | 'todos'
+    | 'files'
     | 'members'
     | 'activity'
     | 'settings';
@@ -34,6 +36,7 @@ export function ProjectNav({
     notes: active === 'notes',
     chat: active === 'chat',
     todos: active === 'todos',
+    files: active === 'files',
     members: active === 'members',
     activity: active === 'activity',
     settings: active === 'settings',