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>

local-instance/scripts/minio-init.sh

@@ -11,9 +11,16 @@ for bucket in \
 	h5p-content-bucket `   # h5p-editor content` \
 	h5p-library-bucket `   # h5p content types` \
 	ydocs `                # tldraw whiteboard documents` \
-	fwu-content            # FWU media, unused but cheap to create
+	fwu-content `          # FWU media, unused but cheap to create` \
+	bucket-5f2987e020834114b8efd6f6 # legacy file manager, demo school (see below)
 do
 	mc mb --ignore-existing "local/$bucket"
 done
 
+# The legacy file manager keeps one bucket per school, "bucket-<schoolId>", and
+# creates it on first upload — then calls PutBucketCors, which MinIO does not
+# implement, so the first upload fails with "A header you provided implies
+# functionality that is not implemented". A bucket that already exists skips
+# both calls. 5f2987e020834114b8efd6f6 is the demo school's fixed seed id.
+
 mc ls local