feat(frontend): enable multi-column search on Flows list

Mark `id`, `title`, and `status` as `meta.searchable: true` so the DataTable picks them up as candidates for the new global-filter search, and drop the explicit `filterColumn="title"` prop so users can search by uuid prefix or by typing a status keyword (e.g. "running"). `provider` and `terminals` stay excluded — both are non-string values that would only emit `[object Object]` matches.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/pages/flows/flows.tsx

@@ -194,6 +194,7 @@ const Flows = () => {
                     />
                 ),
                 maxSize: 80,
+                meta: { searchable: true },
                 minSize: 60,
                 size: 70,
             },
@@ -229,6 +230,7 @@ const Flows = () => {
                         title="Title"
                     />
                 ),
+                meta: { searchable: true },
                 minSize: 200,
                 size: 300,
             },
@@ -255,6 +257,7 @@ const Flows = () => {
                     />
                 ),
                 maxSize: 130,
+                meta: { searchable: true },
                 minSize: 80,
                 size: 100,
             },
@@ -658,7 +661,6 @@ const Flows = () => {
                 <DataTable<Flow>
                     columns={columns}
                     data={flows}
-                    filterColumn="title"
                     filterPlaceholder="Filter flows..."
                     filterValue={filter}
                     onFilterChange={setFilter}