Build 78: honest transport labels, request decline/cancel, NIP-05 on requests, full localization

Settings now says "Manual transaction" and the privacy row reads "Messages &
lookups" opening a new Network privacy page that tells the truth: messages,
names, price and avatars ride the Nym mixnet; the grin node connects directly.
README and lander updated to match.

Requests are messages, payments are final: declining a request now sends the
requester a void control message (NIP-17), a requester can cancel a request they
sent (cancels the local invoice and notifies the payer), and incoming requests
resolve the sender's verified @username instead of a bare npub. The Requested
amount on the success screen is centered. New NostrDecline/NostrCancel tasks and
a goblin-action control message carry it, bound to the stored counterparty.

Localization: every Goblin-screen string moved to t!() keys (370 keys) and
translated into de/fr/ru/tr/zh-CN, guarded by a key/placeholder drift test.
System-locale auto-detect now matches region locales like zh-CN.

src/wallet/types.rs

@@ -450,4 +450,12 @@ pub enum WalletTask {
 	/// Republish our kind-0 profile (e.g. after toggling the incoming-requests
 	/// preference) so the change propagates to relays immediately.
 	NostrRepublishProfile,
+	/// Decline an incoming payment request: mark it declined and send the
+	/// requester a void control message so their side clears too.
+	/// * request id (rumor event id hex)
+	NostrDeclineRequest(String),
+	/// Cancel a request WE sent: cancel the local invoice tx and send the payer a
+	/// void control message so the pending card disappears on their side.
+	/// * slate id (uuid string)
+	NostrCancelOutgoing(String),
 }

src/wallet/wallet.rs

@@ -2364,6 +2364,59 @@ async fn handle_task(w: &Wallet, t: WalletTask) {
 				service.republish_identity().await;
 			}
 		}
+		WalletTask::NostrDeclineRequest(rumor_id) => {
+			let Some(service) = w.nostr_service() else {
+				return;
+			};
+			let Some(mut request) = service.store.request(rumor_id) else {
+				error!("nostr decline: request not found");
+				return;
+			};
+			// Mark declined locally (idempotent) so the card stays gone, then tell
+			// the requester. Requests are messages; payments are final.
+			request.status = crate::nostr::RequestStatus::Declined;
+			service.store.save_request(&request);
+			if let Err(e) = service
+				.send_control_dm(&request.npub, &request.slate_id, &[])
+				.await
+			{
+				error!("nostr decline: control dispatch failed: {e}");
+			}
+		}
+		WalletTask::NostrCancelOutgoing(slate_id) => {
+			let Some(service) = w.nostr_service() else {
+				return;
+			};
+			let Some(meta) = service.store.tx_meta(slate_id) else {
+				error!("nostr cancel: no metadata for slate {slate_id}");
+				return;
+			};
+			if meta.direction != crate::nostr::NostrTxDirection::RequestedByUs {
+				error!("nostr cancel: slate {slate_id} is not an outgoing request");
+				return;
+			}
+			// Cancel the underlying grin invoice tx (an issued invoice locks no
+			// outputs, but cancelling keeps the wallet ledger tidy).
+			if let Some(tx_id) = w.get_data().and_then(|d| d.txs).and_then(|txs| {
+				txs.iter()
+					.find(|t| {
+						t.data.tx_slate_id.map(|u| u.to_string()).as_deref()
+							== Some(slate_id.as_str())
+					})
+					.map(|t| t.data.id)
+			}) {
+				if let Err(e) = w.cancel(tx_id) {
+					error!("nostr cancel: wallet cancel failed: {e}");
+				}
+			}
+			service
+				.store
+				.update_tx_status(slate_id, crate::nostr::NostrSendStatus::Cancelled);
+			if let Err(e) = service.send_control_dm(&meta.npub, slate_id, &[]).await {
+				error!("nostr cancel: control dispatch failed: {e}");
+			}
+			sync_wallet_data(&w, false);
+		}
 		WalletTask::NostrResend(id) => {
 			let Some(service) = w.nostr_service() else {
 				return;