feat: enhance opportunity detail and sales flow

src/components/SessionGuard.svelte

@@ -0,0 +1,39 @@
+<script lang="ts">
+  import { onMount, onDestroy } from "svelte";
+  import { goto } from "$app/navigation";
+
+  const INTERVAL_MS = 60_000; // 60 seconds
+
+  let timer: ReturnType<typeof setInterval> | null = null;
+
+  async function checkSession() {
+    try {
+      const res = await fetch("/api/auth/check", {
+        credentials: "same-origin",
+      });
+
+      if (!res.ok) {
+        // Session is dead — redirect to login
+        console.warn("Session expired or invalid — redirecting to login.");
+        goto("/login");
+      }
+    } catch (err) {
+      // Network error (API unreachable, etc.) — don't redirect on transient
+      // failures; the next tick will retry.
+      console.warn("Session check failed (network error):", err);
+    }
+  }
+
+  onMount(() => {
+    // Run the first check immediately, then every 60 s
+    checkSession();
+    timer = setInterval(checkSession, INTERVAL_MS);
+  });
+
+  onDestroy(() => {
+    if (timer) {
+      clearInterval(timer);
+      timer = null;
+    }
+  });
+</script>