fix(datatables): clone a fork's pointer instead of failing after the copy

Forking a fork with cloning left an orphan database. The preflight resolves the
pointer and sees the governing entry, so both endpoints ran and filled the new
database; `apply_forked_datatable` then refused the inherited pointer and rolled
the fork back, stranding a registered `wm_fork_*` that no entry names and whose
name blocks the retry.

Refusing earlier would have been the smaller change, but forking a fork and
cloning worked before pointers existed, so it would trade an orphan for a
regression. Resolve what the pointer names and write the terminal entry the
clone needs: the whole `database` object rather than a patch of its
`resource_path`, since a pointer has none, and `reference` removed with it.

Also accepts `-- role=x` and `-- Role = x`, two more spellings that fell through
to the default role.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BjfMkJyKzodxkobqGZ6Lqb

backend/.sqlx/query-ebaf3ed3097621da59dd201b5a4b9d1f440692f183c7c378f59e4b73f1c6e241.json

@@ -0,0 +1,17 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "UPDATE workspace_settings\n               SET datatable = jsonb_set(\n                   jsonb_set(\n                       datatable #- ARRAY['datatables', $2, 'reference'],\n                       ARRAY['datatables', $2, 'database'], $3::jsonb),\n                   ARRAY['datatables', $2, 'forked_from'], $4::jsonb\n               )\n               WHERE workspace_id = $1",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Text",
+        "Text",
+        "Jsonb",
+        "Jsonb"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "ebaf3ed3097621da59dd201b5a4b9d1f440692f183c7c378f59e4b73f1c6e241"
+}