backend: Patient Portal over the relay + wallet linking

- services/portal.ts: clinic-scoped portal actions (clinic info, doctors,
  availability, linkWallet, conflict-checked booking, results, downloadable lab
  files) plus handlePortalRequest to dispatch a relayed portal:request.
- relay-client.ts: handle portal:request on the hub and ack the result back down
  the relay (device path identifies the patient by verified wallet number).
- patients: new nullable wallet_number column (+ migration); linking stores it,
  and walletNumberForPatient now resolves via it so pushes work after a portal
  link, not only after a permanent share.
- routes/portal.ts: GET /:clinic/link returns the relay-based pairing descriptor
  (clinic signing key + relay URL) for the QR — no more localhost-baked API URL.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/routes/portal.ts

@@ -5,6 +5,7 @@ import { z } from "zod";
 import { db } from "../db/index.js";
 import { member, organization, user } from "../db/schema/auth.js";
 import { staffProfile } from "../db/schema/staff-profile.js";
+import { env } from "../env.js";
 import { appointmentInputSchema } from "../lib/appointment-validation.js";
 import { HttpError } from "../lib/http-error.js";
 import { initialsFromName } from "../lib/initials.js";
@@ -12,6 +13,7 @@ import { patientInputSchema } from "../lib/patient-validation.js";
 import { recordActivity } from "../services/activity.js";
 import { createAppointment, listAppointments } from "../services/appointments.js";
 import { createPatient, getPatient } from "../services/patients.js";
+import { getOrCreateKey } from "../services/signing.js";
 
 // Clinical-capable roles that can be a patient's provider (mirrors
 // staff.ts PROVIDER_ROLES). Department roles (reception, pharmacy, lab) excluded.
@@ -50,6 +52,27 @@ portalRouter.get("/:clinic", async (req, res, next) => {
   }
 });
 
+// GET /api/portal/:clinic/link — the relay-based pairing descriptor the wallet
+// app scans to talk to this clinic over the Temetro Network: the clinic's
+// signing public key (the relay's routing id) + the relay URL. Both values are
+// non-secret (the signing key is the clinic's public identity). This is what
+// makes the Patient Portal QR reachable from a real phone — it no longer bakes
+// in a localhost API URL.
+portalRouter.get("/:clinic/link", async (req, res, next) => {
+  try {
+    const clinic = await resolveClinic(req);
+    const key = await getOrCreateKey(clinic.id);
+    res.json({
+      clinicId: key.publicKey,
+      relay: env.RELAY_URL,
+      slug: String(req.params.clinic ?? "").trim(),
+      name: clinic.name,
+    });
+  } catch (err) {
+    next(err);
+  }
+});
+
 // GET /api/portal/:clinic/doctors — public list of the clinic's providers so a
 // patient can pick who to see. Returns only display-safe fields (name +
 // specialty); no ids, emails, or usernames leave this unauthenticated surface.