Show session expiry warning in statusline

When the fetcher gets a 401/403, it writes an error state to the cache
file instead of silently failing. The statusline reads this and shows
"Token: session expired — refresh cookie" so the user knows to re-extract
the sessionKey cookie from claude.ai.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

statusline.js

@@ -41,8 +41,12 @@ function readCache() {
     if (!fs.existsSync(CACHE_FILE)) return null;
     const stat = fs.statSync(CACHE_FILE);
     const ageS = (Date.now() - stat.mtimeMs) / 1000;
+    const data = JSON.parse(fs.readFileSync(CACHE_FILE, 'utf8'));
+    // Error state written by fetcher — always show regardless of age
+    if (data._error) return data;
+    // Normal data — respect max age
     if (ageS > CACHE_MAX_AGE_S) return null;
-    return JSON.parse(fs.readFileSync(CACHE_FILE, 'utf8'));
+    return data;
   } catch {
     return null;
   }
@@ -60,6 +64,11 @@ function formatMinutes(isoStr) {
 
 function getUsagePart(data) {
   if (!data) return '';
+
+  // Error state from fetcher
+  if (data._error === 'auth_expired') return 'Token: session expired — refresh cookie';
+  if (data._error) return 'Token: fetch error';
+
   const parts = [];
 
   if (data.five_hour && data.five_hour.utilization > 0) {