feat(system): show where the library lives and offer the move

D129. System > Overview's Library health gains a "Library location" row
(the database path, why it is there, the "Keep it here" choice and any
PROMPT_MANAGER_DATA_DIR problem) with Move library for a node-folder
library and Details otherwise. While a node-folder library is not kept
there, the workspace shows the concept's .notice above every page:
"Keep it here" saves the choice on the server and stops the notice;
"Move library" opens the shared review (From, To, Size, what moves, what
happens to the old files) and starts the exclusive job in Activity. The
notice and the Overview read the location again when the job ends.

The Overview comparison maps the inserted row; a new comparison holds the
notice to the concept's Sources notice (markup, tokens, alignment, both
themes and widths) with a mutation check.

tests/browser/workspace_system_fixture.py

@@ -23,6 +23,12 @@ read. These per-server hooks only change what a System test needs on top:
   image monitor whose observer is ``alive`` (default true) and schedules the
   named folders of this server's root (``["output"]``), so Sources reads
   watching, manual scan and restart pending states (S4).
+- ``POST /__test__/system/library`` ``{state}`` (S6b): ``node_folder`` makes
+  the live database read as a node-folder library that can move to
+  ``user/__promptmanager``; Move library then runs a stand-in move that
+  touches no file and ends with the library in the default folder.
+  ``failing`` is the same library whose move fails verification. Reset
+  restores the real resolver, the real move and "Keep it here".
 
 Delays use the shared request holds (``request_hold.py``).
 """
@@ -54,7 +60,12 @@ def register_system_commands(app, routes, api, root: Path):
     from py.config import GalleryConfig, PromptManagerConfig
     from utils import image_monitor
 
+    from database import library_move
+    from utils import library_location
+
     configured = list(GalleryConfig.MONITORING_DIRECTORIES)
+    real_move = library_move.move_library
+    keep = PromptManagerConfig.KEEP_LIBRARY_IN_NODE_FOLDER
     config_bytes = config_path.read_bytes() if config_path.exists() else None
     host_values = (
         PromptManagerConfig.RESULT_TIMEOUT,
@@ -92,6 +103,9 @@ def register_system_commands(app, routes, api, root: Path):
             GalleryConfig.MONITORING_ENABLED,
         ) = host_values
         image_monitor._monitor_instance = monitor
+        api.__dict__.pop("_library_resolver", None)
+        library_move.move_library = real_move
+        PromptManagerConfig.KEEP_LIBRARY_IN_NODE_FOLDER = keep
         if config_bytes is None:
             config_path.unlink(missing_ok=True)
         else:
@@ -187,6 +201,43 @@ def register_system_commands(app, routes, api, root: Path):
         )
         return web.json_response({"success": True})
 
+    @routes.post("/__test__/system/library")
+    async def library_state(request):
+        data = await request.json()
+        state = data.get("state")
+        if state not in ("node_folder", "failing"):
+            raise web.HTTPBadRequest()
+        target = str(root / "user" / "__promptmanager")
+
+        def located(source):
+            return library_location.LibraryLocation(
+                source,
+                api.db.model.db_path,
+                str(config_path),
+                str(root),
+                target if source == library_location.SOURCE_NODE_FOLDER else None,
+                target_source=library_location.SOURCE_DEFAULT,
+            )
+
+        current = {"source": library_location.SOURCE_NODE_FOLDER}
+        api._library_resolver = lambda: located(current["source"])
+
+        def stand_in_move(plan, *, progress, **_kwargs):
+            if state == "failing":
+                raise library_move.MoveFailed("verify-failed")
+            progress("Copying the database")
+            counts = api.db.library_counts()
+            current["source"] = library_location.SOURCE_DEFAULT
+            return library_move.MoveResult(
+                located(library_location.SOURCE_DEFAULT),
+                {"prompts": counts["positive_prompts"], "generated_images": 0},
+                ["prompts.db"],
+                ["browser.db.moved-to-__promptmanager"],
+            )
+
+        library_move.move_library = stand_in_move
+        return web.json_response({"success": True})
+
     return reset