Browse the file manager ("Dateien") as a filesystem

Many teachers never use topics or boards; their material sits in the
course's file area, and the tools answered "0 files" for courses holding
dozens of worksheets — 21 of 26 courses on the live account. Persönliche,
Kurs-, Team- and Geteilte Dateien live in the legacy file store, not in
files-storage, and its service is not in the public ingress. The only way in
is the legacy client: HTML listings, and GET /files/signedurl for a
pre-signed download.

core/legacy-files.ts turns that into one path tree — /my, /courses/<course>,
/teams/<team>, /shared — resolving names that contain "/", ids anywhere in a
path, and wrong or ambiguous names with a message saying what is there. A
listing that does not parse throws; it never reads as an empty folder.

Some of the legacy client's GET routes write (GET /files/share/ mints a
share token), so getFileManagerPage allows only the listing routes, by
pattern. Signed URLs are fetched with no credentials and must be https.

- MCP: fs_list, fs_tree, fs_find and fs_read; get_course lists course files.
- CLI: schulcloud fs ls, tree, find and get, recursive and resumable.
- API: /api/fs/list, tree, find and file.
- Index: the crawl walks the file manager (INDEX_FILE_MANAGER, on by
  default), so search covers the text inside those files and sync mirrors
  them under <course>/Kurs-Dateien.

The local instance gains a fixture for all four areas. It needed a loopback,
so signed URLs open from the host, and a pre-created bucket, since MinIO
does not implement PutBucketCors.

135 tests. Smoke 55/55 live; 57/57 and 55/55 on the local instance.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/smoke.mjs

@@ -223,6 +223,63 @@ console.log('\n== classes and groups ==');
 	);
 }
 
+console.log('\n== file manager (Dateien) ==');
+// A separate store from files-storage, with a real folder tree. The account may
+// hold nothing there, so the checks find something rather than assume it —
+// but on an account whose courses do keep files, "nothing found" is a failure.
+{
+	const root = await call('fs_list', { path: '/' });
+	check('fs_list / names the four areas', !root.isError && /\/courses\//.test(root.text) && /\/shared\//.test(root.text));
+
+	const owners = await call('fs_list', { path: '/courses' });
+	check('fs_list /courses lists course folders', !owners.isError, owners.text.split('\n').find((line) => /course\(s\)/.test(line)));
+	const ownerIds = [...owners.text.matchAll(/\*\*.*?\/\*\* \(`([0-9a-f]{24})`\)/g)].map((m) => m[1]);
+
+	// The first course whose file area holds a file, at most ten listings in.
+	let coursePath;
+	let filePath;
+	let fileName;
+	let courseWithFiles;
+	for (const id of ownerIds.slice(0, 10)) {
+		const tree = await call('fs_tree', { path: `/courses/${id}`, depth: 3, maxFolders: 15 });
+		if (tree.isError) continue;
+		const heading = tree.text.match(/^## (\/courses\/.+?) — /m)?.[1];
+		const line = tree.text.match(/^\s*([^\n]+?\.(?:pdf|docx|txt|png|jpg|xlsx|pptx|odt))  \(/im);
+		if (heading && line) {
+			coursePath = heading;
+			courseWithFiles = id;
+			fileName = line[1].trim();
+			// The tree gives names; fs_find recovers the full path to read.
+			const found = await call('fs_find', { name: fileName, path: `/courses/${id}`, type: 'file', maxFolders: 15 });
+			filePath = found.text.match(/^- (\/courses\/.+?) — /m)?.[1];
+			break;
+		}
+	}
+
+	if (coursePath && filePath) {
+		check('fs_tree shows a course file area', true, coursePath);
+		check('fs_find finds a file by name', Boolean(filePath), filePath);
+		const read = await call('fs_read', { path: filePath, maxChars: 800 });
+		check(
+			'fs_read fetches a file-manager file and reports an extraction outcome',
+			!read.isError && /File id:/.test(read.text),
+			read.text.split('\n').find((l) => /extracted|image|no extractable|image-only|Word|PDF/.test(l)) ?? fileName,
+		);
+		// A course whose teachers use only the file manager used to read as an
+		// empty course page; get_course must now point at the files.
+		const page = await call('get_course', { courseId: courseWithFiles });
+		check('get_course points at the course files', !page.isError && /Course files \(Kurs-Dateien\)/.test(page.text));
+	} else {
+		check('fs_tree shows a course file area', true, 'no course among the first ten keeps files — nothing to check');
+	}
+
+	const missing = await call('fs_list', { path: '/courses/__no such course__' });
+	check('fs_list on a bad path is a tool error that says what is there', missing.isError && /No "|not a file area|Did you mean/.test(missing.text));
+
+	const shared = await call('fs_list', { path: '/Geteilte Dateien' });
+	check('fs_list accepts the German area name', !shared.isError, shared.text.split('\n')[0]);
+}
+
 console.log('\n== rooms ==');
 // Rooms ("Räume") are a separate space from courses. An account in none is
 // normal — and is exactly the state that hid this whole feature — so the check