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.

web/workspace.html

@@ -40,6 +40,8 @@
                             <option value="system" selected>System</option>
                         </select></label><a class="canvas-link" href="../">ComfyUI <span aria-hidden="true">↗</span></a></div>
             </header>
+            <!-- D129: the library-location notice, shown above every page while a node-folder library can move. -->
+            <div id="library-banner" class="library-banner" hidden></div>
             <main id="workspace-main" tabindex="-1"></main>
             <footer class="app-footer"><span>ComfyAssets · Local tools. Your library.</span></footer>
         </div>