feat(web): responsive object detail (pane/drawer) at canonical /objects/:id (#44, #58)

Wide (>=1024px): right-hand pane beside the table with a close control.
Narrow: Base UI Drawer sliding from the right (lazy-loaded so its code splits
out of the main chunk). Both preserve the table's query string on close.

Remove the index SelectPrompt route (the table is the landing view) and delete
the now-unused SelectPrompt. Make table rows keyboard-activatable
(role=link, tabIndex, Enter).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/objects/objects-table.tsx

@@ -246,8 +246,13 @@ export function ObjectsTable() {
           return (
             <tr
               key={object.id}
+              role="link"
+              tabIndex={0}
               aria-selected={selected}
               onClick={() => navigate(`/objects/${object.id}?${params}`)}
+              onKeyDown={(event) => {
+                if (event.key === "Enter") navigate(`/objects/${object.id}?${params}`);
+              }}
               className={`cursor-pointer border-b text-sm ${
                 selected ? "bg-indigo-50" : "hover:bg-neutral-50"
               }`}