fix: route terminal callbacks and status per session

The recent redraw fix keeps all xterm instances mounted (display:none)
when switching sessions. However, sendData/focus/font-size refs and the
header connection status were still stored globally, so the last-mounted
hidden session could own keyboard input, font-size buttons, and the
status dot for the active session.

- Pass sessionId to onTerminalReady from TerminalComponent.
- Store terminal callbacks and status keyed by sessionId in use-terminal-page.
- Use activeSessionId to route special-key input, font-size changes, and header status.
- Clean up per-session refs and status when sessions are closed.
- Update MobileTerminalWrapper signature for the new callback shape.

Quality gates: npm run typecheck, npm run lint, npm test (87 passed)

apps/web/src/components/features/mobile/mobile-terminal-wrapper.tsx

@@ -27,10 +27,17 @@ export const MobileTerminalWrapper: React.FC<MobileTerminalWrapperProps> = ({
   const { isOpen: isKeyboardOpen, height: keyboardHeight } =
     useVirtualKeyboard();
   const [showPanel, setShowPanel] = useState(false);
-  const [activeModifier, setActiveModifier] = useState<ModifierKey | null>(null);
+  const [activeModifier, setActiveModifier] = useState<ModifierKey | null>(
+    null,
+  );
   const [terminalRef, setTerminalRef] = useState<{
     sendData: (data: string) => void;
-    connectionStatus: "connecting" | "connected" | "disconnected" | "error" | "resetting";
+    connectionStatus:
+      | "connecting"
+      | "connected"
+      | "disconnected"
+      | "error"
+      | "resetting";
     focusInput: () => void;
     changeFontSize: (delta: number) => void;
   } | null>(null);
@@ -42,17 +49,33 @@ export const MobileTerminalWrapper: React.FC<MobileTerminalWrapperProps> = ({
   }, [headerAutoHide]);
 
   const handleTerminalReady = useCallback(
-    (sendData: (data: string) => void, connectionStatus: "connecting" | "connected" | "disconnected" | "error" | "resetting", focusInput: () => void, changeFontSize: (delta: number) => void) => {
-      setTerminalRef({ sendData, connectionStatus, focusInput, changeFontSize });
+    (
+      _sessionId: string | undefined,
+      sendData: (data: string) => void,
+      connectionStatus:
+        | "connecting"
+        | "connected"
+        | "disconnected"
+        | "error"
+        | "resetting",
+      focusInput: () => void,
+      changeFontSize: (delta: number) => void,
+    ) => {
+      setTerminalRef({
+        sendData,
+        connectionStatus,
+        focusInput,
+        changeFontSize,
+      });
     },
-    []
+    [],
   );
 
   const handleSendKey = useCallback(
     (data: string) => {
       terminalRef?.sendData(data);
     },
-    [terminalRef]
+    [terminalRef],
   );
 
   if (!isMobile) {