Palette: keep focus in the search input so Enter only searches

Clicking the + follow toggle used to move focus onto that button, so the
next Enter re-triggered the follow instead of searching the highlighted
tag. The toggle now prevents the mouse-down focus steal, and the footer
hint spells out that Enter searches while + follows.

frontend/src/components/CommandPalette.tsx

@@ -423,7 +423,7 @@ function CommandPaletteDialog({ onClose }: { onClose: () => void }) {
         <div className="flex items-center gap-3 border-t border-ctp-surface1 px-4 py-2 text-[10px] text-ctp-overlay0">
           <span className="flex items-center gap-1.5">
             <Images className="h-3 w-3 shrink-0" /> Enter searches the
-            highlighted tag · + follows it
+            highlighted tag — the + button only follows/unfollows
           </span>
           <span className="ml-auto font-mono">↑↓ · Esc</span>
         </div>

frontend/src/features/follows/TagFollowToggle.tsx

@@ -66,6 +66,11 @@ export function TagFollowToggle({ tag }: { tag: string }) {
     <button
       type="button"
       onClick={handleClick}
+      onMouseDown={(event) => {
+        // Keep focus where it was (e.g. the Ctrl+K input) so a following
+        // Enter press searches instead of re-triggering this toggle.
+        event.preventDefault();
+      }}
       disabled={busy || query.isPending}
       title={error ?? (followed ? `Unfollow ${tag}` : `Follow ${tag}`)}
       aria-label={followed ? `Unfollow ${tag}` : `Follow ${tag}`}