Initial commit: thbd-portal, duplicated from elmi-portal

Rebranded for Thunderbird Portal (THBD): numbering prefix EL->TH, all
"ELMI"/"ЭЛМИ" UI strings genericized, ELMI's real contract templates and
company legal/bank details removed (not applicable to this company), fresh
VAPID keypair and encryption key, fresh single-migration schema history.
Same architecture as elmi-portal: Web Push notifications, unread-chat app
badge, cookie-session auth.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gh2UXUQUVBWroWEnn1FLFG

public/sw.js

@@ -0,0 +1,53 @@
+// Web Push service worker. Deliberately minimal — no offline caching, no
+// asset interception. Its only job is to keep receiving push events even
+// when the page's own tab is frozen or closed, and turn them into an OS
+// notification.
+
+self.addEventListener("push", (event) => {
+  let payload = { title: "Thunderbird Portal", body: "", url: "/inquiries" };
+  try {
+    if (event.data) payload = { ...payload, ...event.data.json() };
+  } catch {
+    // malformed payload — fall back to the generic notification above
+  }
+
+  event.waitUntil(
+    (async () => {
+      await self.registration.showNotification(payload.title, {
+        body: payload.body,
+        icon: "/icon-192.png",
+        data: { url: payload.url },
+      });
+
+      // badgeCount is only present on payloads that affect the unread chat
+      // count — other event types omit it entirely so the badge is left
+      // alone. Android/desktop only; iOS Safari has no Badging API (the
+      // calls just don't exist there, so this is a no-op, not an error).
+      if (typeof payload.badgeCount === "number" && "setAppBadge" in self.navigator) {
+        if (payload.badgeCount > 0) {
+          await self.navigator.setAppBadge(payload.badgeCount);
+        } else {
+          await self.navigator.clearAppBadge();
+        }
+      }
+    })(),
+  );
+});
+
+self.addEventListener("notificationclick", (event) => {
+  event.notification.close();
+  const url = event.notification.data && event.notification.data.url ? event.notification.data.url : "/inquiries";
+
+  event.waitUntil(
+    (async () => {
+      const clientsList = await self.clients.matchAll({ type: "window", includeUncontrolled: true });
+      const existing = clientsList.find((c) => "focus" in c);
+      if (existing) {
+        await existing.navigate(url);
+        await existing.focus();
+        return;
+      }
+      await self.clients.openWindow(url);
+    })(),
+  );
+});