fix: prevent infinite reload loop on stale build recovery

Use sessionStorage guard so the hard reload only fires once. If the
reload doesn't fix it (CDN still serving stale JS), fall through
gracefully instead of looping forever.

app/auth/callback/page.tsx

@@ -26,8 +26,15 @@ function AuthCallbackContent() {
     try {
       result = await exchangeAuthCode(code, codeVerifier, redirectUri)
     } catch {
-      // * Stale build — cached JS has old Server Action hashes. Hard reload to fix.
-      window.location.reload()
+      // * Stale build — cached JS has old Server Action hashes. Hard reload once to fix.
+      const key = 'pulse_reload_for_stale_build'
+      if (!sessionStorage.getItem(key)) {
+        sessionStorage.setItem(key, '1')
+        window.location.reload()
+        return
+      }
+      sessionStorage.removeItem(key)
+      setError('Something went wrong. Please try logging in again.')
       return
     }
     if (result.success && result.user) {