fix: resolve terminal WebSocket auth failures and improve reconnection

- Remove insecure query token parameter from backend (cookie-only auth)
- Add detailed JWT error logging (expired, invalid, missing tokens)
- Force token refresh before first WebSocket connection
- Stop reconnection after 3 consecutive auth failures
- Increase ping interval from 12s to 30s (reduce traffic)
- Increase pong timeout from 5s to 10s (handle network latency)
- Show attempt counter in reconnection error messages

Root cause: Frontend was reconnecting with 6-day-old expired token,
causing 403 rejections. Now ensures fresh cookies before connecting.

dashboard/frontend/src/routes/Terminal.svelte

@@ -196,8 +196,11 @@
       let reconnecting = false;
       let authRecoveryInFlight = false;
       let reconnectAttempts = 0;
+      let consecutiveAuthFailures = 0;
       const MAX_RECONNECT_DELAY = 30000;
-      const PONG_TIMEOUT = 5000; // 5s to receive pong
+      const MAX_AUTH_FAILURES = 3;
+      const PING_INTERVAL = 30000; // 30s between pings
+      const PONG_TIMEOUT = 10000; // 10s to receive pong
 
       function clearHeartbeat() {
         if (heartbeat) {
@@ -263,12 +266,18 @@
       }
 
       async function connect(forceRefresh = false) {
-        if (forceRefresh) {
+        // Always refresh token before first connection to ensure fresh cookies
+        const d = tabData.get(tabId);
+        const isFirstConnect = !d?.hasConnectedOnce;
+
+        if (forceRefresh || isFirstConnect) {
           const refreshed = await tryRefreshSession();
           if (!refreshed) {
             handleAuthExpired();
             return null;
           }
+          // Mark that we've connected once with fresh token
+          if (d) d.hasConnectedOnce = true;
         }
 
         const ws = new WebSocket(
@@ -278,6 +287,7 @@
 
         ws.onopen = () => {
           reconnectAttempts = 0;
+          consecutiveAuthFailures = 0; // Reset auth failure counter on successful connection
           updateTab(tabId, {
             connected: true,
             error: "",
@@ -295,7 +305,7 @@
                 }
               }, PONG_TIMEOUT);
             }
-          }, 12000);
+          }, PING_INTERVAL);
           const d = tabData.get(tabId);
           if (d) {
             d.ws = ws;
@@ -335,7 +345,18 @@
           const reason = e.reason || `Connection closed (code ${e.code})`;
           const d = tabData.get(tabId);
           if (d) d.ws = null;
-          if (e.code === 1008 && reason === "Unauthorized") {
+
+          // Handle auth failures (code 1008)
+          if (e.code === 1008) {
+            consecutiveAuthFailures++;
+
+            // Stop after MAX_AUTH_FAILURES consecutive auth failures
+            if (consecutiveAuthFailures >= MAX_AUTH_FAILURES) {
+              handleAuthExpired(`Session expired after ${MAX_AUTH_FAILURES} attempts — please refresh page`);
+              return;
+            }
+
+            // Try to refresh session
             if (!closedManually && !authRecoveryInFlight) {
               authRecoveryInFlight = true;
               const refreshed = await tryRefreshSession();
@@ -344,7 +365,7 @@
                 reconnecting = true;
                 updateTab(tabId, {
                   connected: false,
-                  error: "Refreshing session...",
+                  error: `Refreshing session (attempt ${consecutiveAuthFailures}/${MAX_AUTH_FAILURES})...`,
                   statusBanner: tab.persistent ? "Reconnecting to persistent session..." : "",
                 });
                 term.write(`\r\n\x1b[90m[Refreshing session...]\x1b[0m`);
@@ -355,6 +376,8 @@
             handleAuthExpired("Session expired — please log in again");
             return;
           }
+
+          // Non-auth failures: continue with normal reconnection
           if (!closedManually) scheduleReconnect(reason);
           else {
             clearHeartbeat();