L12/COR-011: add foreground idle autolock interval for native (Android)

@@ -502,6 +502,33 @@502502           stopSyncPolling();503503         });504504       }505+506+      // L12/COR-011: foreground idle autolock. appStateChange only fires when507+      // the OS backgrounds the app — if the user idles with the screen on,508+      // chrome.alarms is no-op'd in Capacitor so the vault would stay open509+      // indefinitely. Poll every 30s and lock if elapsed since last user510+      // interaction exceeds autoLockMinutes.511+      let lastUserActivityAt = Date.now();512+      const bumpActivity = () => { lastUserActivityAt = Date.now(); };513+      const ACTIVITY_EVENTS = ["touchstart", "click", "keydown", "input"] as const;514+      for (const ev of ACTIVITY_EVENTS) {515+        document.addEventListener(ev, bumpActivity, { passive: true, capture: true });516+      }517+      const idleLockInterval = setInterval(() => {518+        const minutes = autoLockMinutes();519+        if (!minutes || minutes <= 0) return;520+        const elapsed = Date.now() - lastUserActivityAt;521+        if (elapsed >= minutes * 60_000) {522+          lastUserActivityAt = Date.now();523+          handleHeaderLock();524+        }525+      }, 30_000);526+      onCleanup(() => {527+        clearInterval(idleLockInterval);528+        for (const ev of ACTIVITY_EVENTS) {529+          document.removeEventListener(ev, bumpActivity, { capture: true });530+        }531+      });505532     }506533 507534     // Background auto-lock broadcasts VAULT_LOCKED so the popup drops stale