Fix annoying DM relay warning and clarify settings UI

- Throttle the "Privacy warning: direct messages are using your default relays..." message so it only appears once per session/identity change.
- Rename "DM Relay Hints" to "NIP-17 Relay List" in the DM Settings modal to match the warning message and reduce user confusion.
- Add regression test for the warning throttling logic.

Co-authored-by: PR0M3TH3AN <[email protected]>

js/ui/profileModalController.js

@@ -1042,6 +1042,7 @@ export class ProfileModalController {
     this.adminSuperNpub = resolvedAdminSuperNpub;
     this.adminDmImageUrl = resolvedAdminDmImageUrl;
     this.bitvidWebsiteUrl = resolvedbitvidWebsiteUrl;
+    this.hasShownRelayWarning = false;
 
     this.internalState = {
       savedProfiles: [],
@@ -2795,6 +2796,7 @@ export class ProfileModalController {
       ? this.normalizeHexPubkey(actorPubkey)
       : this.resolveActiveDmActor();
 
+    this.hasShownRelayWarning = false;
     this.setDirectMessageRecipient(null, { reason: "clear" });
     this.resetAttachmentQueue({ clearInput: true });
     this.dmReadReceiptCache.clear();
@@ -5374,6 +5376,11 @@ export class ProfileModalController {
       return;
     }
 
+    if (this.hasShownRelayWarning) {
+      return;
+    }
+    this.hasShownRelayWarning = true;
+
     this.showStatus(
       "Privacy warning: direct messages are using your default relays because no NIP-17 relay list is available.",
       { autoHideMs: 5000 },