agent term: move expand-tool-output setting into its own settings popup

mara, #3778: the toggle lived on the separate hive-dashboard's
/settings.html even though it's agent-terminal-only. Moved it into
SettingsMenu (shared with swarm-ui) behind an opt-in showExpandDetails
prop — only the agent page passes it, matching her caution that the
component is shared but this setting isn't.

Also found and fixed a real regression while touching this: the
Preact rewrite's classifyEvent.ts hardcodes defaultOpen: true only for
the always-open markdown-bearing rows (send/ask/answer/recv) and never
reads the preference at all for the rows it's actually meant to
control (diffs, plain tool output, long errors) — so the toggle
currently has zero effect on the live page. Wired
getExpandDetailsPref() into those four sites; the always-open rows are
untouched, matching the documented pre-rewrite behavior.

Converted prefs.js to prefs.ts (TS couldn't resolve types for a plain
.js import) — same public @hive/shared/prefs.js export path, matching
how badge.js/icons.js etc. already map a .js export name to a
.tsx/.ts source file.

frontend/packages/shared/src/prefs.ts

@@ -13,15 +13,20 @@ const EXPAND_DETAILS_KEY = 'hive-agent-expand-details';
 // client-side — no backend field, nothing round-trips through
 // `/api/*`. Read live (not cached) by the shared terminal factory's
 // `expandDetails` option — see docs/web-ui/shape.md::Shared terminal
-// pane — so a preference change on /settings.html applies to the next
-// rendered row in any already-open agent tab without a reload.
-export function getExpandDetailsPref() {
-  try { return localStorage.getItem(EXPAND_DETAILS_KEY) === '1'; }
-  catch { return false; }
+// pane — so a preference change applies to the next rendered row in
+// any already-open agent tab without a reload.
+export function getExpandDetailsPref(): boolean {
+  try {
+    return localStorage.getItem(EXPAND_DETAILS_KEY) === '1';
+  } catch {
+    return false;
+  }
 }
-export function setExpandDetailsPref(v) {
+export function setExpandDetailsPref(v: boolean): void {
   try {
     if (v) localStorage.setItem(EXPAND_DETAILS_KEY, '1');
     else localStorage.removeItem(EXPAND_DETAILS_KEY);
-  } catch { /* localStorage unavailable — preference is session-only */ }
+  } catch {
+    /* localStorage unavailable — preference is session-only */
+  }
 }

frontend/packages/shared/src/settings/SettingsMenu.tsx

@@ -28,6 +28,7 @@ import { Badge } from '../badge/Badge.js';
 import { GearIcon } from '../icons.js';
 import { useThemeOverride, type ThemeOverride } from './theme-apply.js';
 import { useMotionOverride, type MotionOverride } from './motion-apply.js';
+import { getExpandDetailsPref, setExpandDetailsPref } from '../prefs.js';
 import './SettingsMenu.css';
 
 const THEME_OPTIONS: ThemeOverride[] = ['system', 'light', 'dark'];
@@ -36,13 +37,29 @@ const MOTION_OPTIONS: MotionOverride[] = ['system', 'allow', 'reduce'];
 export interface SettingsMenuProps {
   themeKey: string;
   motionKey: string;
+  /**
+   * Show the "expand tool output panels" toggle — agent-terminal-only,
+   * formerly its own section on the (separate) hive dashboard's
+   * `/settings.html`. `SettingsMenu` is shared with swarm-ui too, which
+   * has no terminal to apply this to (mara: "settigs dropdown is
+   * shared component, but the setting is only in the agent term") — so
+   * it's opt-in per consumer rather than always rendered. Only the
+   * agent page passes this; swarm-ui's `Shell` doesn't.
+   */
+  showExpandDetails?: boolean;
 }
 
-export function SettingsMenu({ themeKey, motionKey }: SettingsMenuProps) {
+export function SettingsMenu({ themeKey, motionKey, showExpandDetails }: SettingsMenuProps) {
   const [open, setOpen] = useState(false);
   const rootRef = useRef<HTMLDivElement>(null);
   const [theme, setTheme] = useThemeOverride(themeKey);
   const [motion, setMotion] = useMotionOverride(motionKey);
+  // Plain localStorage read, not a hook-managed override like theme/motion
+  // above — `getExpandDetailsPref`/`setExpandDetailsPref` (`../prefs.js`)
+  // are the existing shared-storage-key pair the terminal itself already
+  // reads live (no round-trip needed here beyond re-rendering this menu's
+  // own checkbox state on toggle).
+  const [expandDetails, setExpandDetailsState] = useState(() => getExpandDetailsPref());
 
   // Close on an outside click or Escape — only listens while open.
   useEffect(() => {
@@ -98,6 +115,20 @@ export function SettingsMenu({ themeKey, motionKey }: SettingsMenuProps) {
               ))}
             </select>
           </label>
+          {showExpandDetails ? (
+            <label class="settings-menu-row">
+              <span>expand tool output</span>
+              <input
+                type="checkbox"
+                checked={expandDetails}
+                onChange={(e) => {
+                  const v = (e.target as HTMLInputElement).checked;
+                  setExpandDetailsPref(v);
+                  setExpandDetailsState(v);
+                }}
+              />
+            </label>
+          ) : null}
         </div>
       ) : null}
     </div>