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.

tests/i18n_keys.rs

@@ -0,0 +1,125 @@
+// Copyright 2026 The Goblin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Localization drift guard. en.yml is the source of truth: every `goblin.*`
+//! key (and its `%{...}` interpolation placeholders) must exist, identically,
+//! in every other locale, so the language picker never falls back to a raw key
+//! or a string that drops a value. Fails CI the moment a translation lags.
+
+use std::collections::{BTreeMap, BTreeSet};
+use std::path::Path;
+
+/// The locales shipped alongside English.
+const OTHER_LOCALES: &[&str] = &["de", "fr", "ru", "tr", "zh-CN"];
+
+/// Flatten a YAML mapping into dotted leaf keys → string value.
+fn flatten(value: &serde_yaml::Value, prefix: &str, out: &mut BTreeMap<String, String>) {
+	match value {
+		serde_yaml::Value::Mapping(map) => {
+			for (k, v) in map {
+				let key = k.as_str().unwrap_or_default();
+				let next = if prefix.is_empty() {
+					key.to_string()
+				} else {
+					format!("{prefix}.{key}")
+				};
+				flatten(v, &next, out);
+			}
+		}
+		other => {
+			let s = match other {
+				serde_yaml::Value::String(s) => s.clone(),
+				serde_yaml::Value::Bool(b) => b.to_string(),
+				serde_yaml::Value::Number(n) => n.to_string(),
+				_ => String::new(),
+			};
+			out.insert(prefix.to_string(), s);
+		}
+	}
+}
+
+/// Load a locale file flattened to `goblin.*` keys only.
+fn load_goblin(locale: &str) -> BTreeMap<String, String> {
+	let path = Path::new(env!("CARGO_MANIFEST_DIR"))
+		.join("locales")
+		.join(format!("{locale}.yml"));
+	let text = std::fs::read_to_string(&path)
+		.unwrap_or_else(|e| panic!("cannot read {}: {e}", path.display()));
+	let doc: serde_yaml::Value =
+		serde_yaml::from_str(&text).unwrap_or_else(|e| panic!("invalid YAML in {locale}.yml: {e}"));
+	let mut all = BTreeMap::new();
+	flatten(&doc, "", &mut all);
+	all.into_iter()
+		.filter(|(k, _)| k.starts_with("goblin."))
+		.collect()
+}
+
+/// `%{name}` placeholders contained in a value, sorted.
+fn placeholders(s: &str) -> BTreeSet<String> {
+	let mut out = BTreeSet::new();
+	let bytes = s.as_bytes();
+	let mut i = 0;
+	while i + 1 < bytes.len() {
+		if bytes[i] == b'%' && bytes[i + 1] == b'{' {
+			if let Some(end) = s[i..].find('}') {
+				out.insert(s[i..i + end + 1].to_string());
+				i += end + 1;
+				continue;
+			}
+		}
+		i += 1;
+	}
+	out
+}
+
+#[test]
+fn every_locale_has_all_goblin_keys() {
+	let en = load_goblin("en");
+	assert!(
+		en.len() > 300,
+		"en.yml goblin block looks too small ({} keys) — did it load?",
+		en.len()
+	);
+	let en_keys: BTreeSet<&String> = en.keys().collect();
+
+	let mut problems = Vec::new();
+	for &loc in OTHER_LOCALES {
+		let other = load_goblin(loc);
+		let other_keys: BTreeSet<&String> = other.keys().collect();
+		for missing in en_keys.difference(&other_keys) {
+			problems.push(format!("{loc}: MISSING key {missing}"));
+		}
+		for extra in other_keys.difference(&en_keys) {
+			problems.push(format!("{loc}: EXTRA key {extra} (not in en.yml)"));
+		}
+		// Placeholder parity: a translation must carry the same %{...} args.
+		for (k, en_val) in &en {
+			if let Some(other_val) = other.get(k) {
+				if placeholders(en_val) != placeholders(other_val) {
+					problems.push(format!(
+						"{loc}: placeholder mismatch in {k} (en {:?} vs {:?})",
+						placeholders(en_val),
+						placeholders(other_val)
+					));
+				}
+			}
+		}
+	}
+
+	assert!(
+		problems.is_empty(),
+		"localization drift detected:\n{}",
+		problems.join("\n")
+	);
+}