Cleanup: dead code, small fixes, Library sorts, old-UI links (#620) (#621)

* refactor: remove dead and test-only code and the write-only prompt registry (#620)

Removes helpers nothing calls, test-only wrappers and their tests, the unused
config writer, three unused images, and the prompt registry the nodes wrote to
but nothing read, which grew with every run.

* fix: network-share readers, model unload off the loop, bad save requests (#620)

Every read-only SQLite open now uses one URI helper, so a library on a Windows
network share works in backups, restores, moves and history reads. Unloading a
model no longer blocks the server. A malformed /save body gets a 400, not a 500.

* feat(library): add Recently used, Most used and Name Z-A sorting (#620)

The old Dashboard's sorts the community asked for, on the Prompt library, in
saved views, and with paging through the whole list.

* feat(workspace): stop linking the old pages (#620)

They show a removal notice since 3.5.1. System no longer links them, the load
failure offers a reload and ComfyUI instead, and the README says they are going
away. The pages still work at their URLs.

database/annotations.py

@@ -291,13 +291,6 @@ class AnnotationOperations:
         conn.execute(_BUMP_INDEX)
         return conn.execute(_REVISION, (byte_id,)).fetchone()[0]
 
-    def _current_set(self, conn, sha256, byte_id, revision) -> dict:
-        return {
-            "sha256": sha256,
-            "tags": self._byte_tags(conn, byte_id),
-            "tag_revision": revision,
-        }
-
     def read_image_tags(self, locator: str, sha256: str) -> dict:
         """The stored set of these exact bytes, or an empty set at revision 0.