fix(versions): scope VLM custom filter per-page to prevent cross-page leak

Store the originating page type alongside VLM data in sessionStorage;
validate it on every page load before applying the filter or showing
the indicator. Stale data is auto-cleaned on mismatch.

This prevents the 'View all local versions' custom filter from leaking
into the checkpoints (or embeddings) page, which caused an empty grid.

static/js/components/controls/CheckpointsControls.js

@@ -101,6 +101,7 @@ export class CheckpointsControls extends PageControls {
             removeSessionItem('vlm_model_id');
             removeSessionItem('vlm_model_name');
             removeSessionItem('vlm_base_model');
+            removeSessionItem('vlm_page_type');
             window.location.reload();
             return;
         }