zap/wallet: flag non-zappable Lightning addresses; per-item settings restore

A static client can't fetch LNURL hosts that omit CORS headers, so zaps to
those creators fail. Add a browser-side reachability probe
(checkLightningAddressZappable) and surface it on both sides: the creator
is warned at wallet-connect time if their own address isn't browser-
zappable, and the zapper sees a heads-up when opening a non-reachable
creator's zap dialog.

Also fix encrypted settings restore: the "already offered" flag was
per-pubkey, so once storage was offered the wallet note was never offered
later. Track it per-item so the wallet is offered independently.
Zappability check extracted to walletZappabilityCheck.js for the size cap.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/ui/profileModal/walletZappabilityCheck.js

@@ -0,0 +1,63 @@
+import { checkLightningAddressZappable } from "../../payments/lnurl.js";
+import { devLogger } from "../../utils/logger.js";
+
+// Warn the creator if their OWN receiving Lightning address can't be reached from
+// a browser (so people can't zap them on bitvid). Best-effort, non-blocking; runs
+// after a successful wallet save. The probe is the exact fetch a zapper's browser
+// would make, so a failure here means a failure for everyone. `controller` is the
+// ProfileWalletController (provides mainController + updateWalletStatus).
+export async function runWalletZappabilityCheck(controller, pubkey) {
+  try {
+    const main = controller?.mainController;
+    const entry =
+      typeof main?.getProfileCacheEntry === "function"
+        ? main.getProfileCacheEntry(pubkey)
+        : null;
+    const profile = entry?.profile || null;
+    // No cached profile -> can't determine; don't guess (avoid a false warning).
+    if (!profile) {
+      return;
+    }
+
+    const address =
+      (typeof profile.lud16 === "string" && profile.lud16.trim()) ||
+      (typeof profile.lud06 === "string" && profile.lud06.trim()) ||
+      "";
+
+    if (!address) {
+      controller.updateWalletStatus(
+        "Wallet saved. Tip: add a Lightning address to your Nostr profile so people can zap you on bitvid.",
+        "info",
+      );
+      return;
+    }
+
+    const result = await checkLightningAddressZappable(address);
+    if (!result.ok) {
+      const message =
+        `Heads up: your Lightning address (${address}) can't be reached from a browser ` +
+        "— its host may be offline or blocking browser requests (no CORS). People may " +
+        "not be able to zap you on bitvid. A host with proper CORS support (e.g. Alby, " +
+        "Coinos, Wallet of Satoshi) fixes this.";
+      controller.updateWalletStatus(message, "error");
+      main.showError(message);
+      return;
+    }
+
+    if (result.reason === "no-nostr") {
+      controller.updateWalletStatus(
+        `Your Lightning address (${address}) is reachable, but its host doesn't advertise ` +
+          "Nostr zaps — payments may work without a zap receipt.",
+        "info",
+      );
+      return;
+    }
+
+    controller.updateWalletStatus(
+      `Wallet saved. Your Lightning address (${address}) is reachable — people can zap you on bitvid.`,
+      "success",
+    );
+  } catch (error) {
+    devLogger.warn("[ProfileModal] Lightning zappability check failed:", error);
+  }
+}