feat(ui): dual-ecash wallet settings, buy-peer-files, seed backup, assorted fixes

- Tabbed Wallet Settings modal (Cashu + Fedimint) and dual-balance wallet card
- Buy a peer's paid file (ecash / node Lightning / on-chain / external QR)
- Recovery-phrase reveal + backup section; onboarding seed retry resilience
- NetBird HTTPS launch, remote-control two-finger scroll + external-open
- Shared BackButton, single-v version label, mesh Bitcoin header toggles

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/src/views/mesh/MeshBitcoinPanel.vue

@@ -1,10 +1,36 @@
 <script setup lang="ts">
-import { ref } from 'vue'
+import { ref, watch } from 'vue'
 import { useMeshStore } from '@/stores/mesh'
 import { rpcClient } from '@/api/rpc-client'
+import ToggleSwitch from '@/components/ToggleSwitch.vue'
 
 const mesh = useMeshStore()
 
+// Bitcoin-headers-over-mesh send/receive toggles (issue #28). Initialized from
+// mesh.status (which now carries the persisted prefs) and saved via mesh.configure.
+const announceHeaders = ref(false)
+const receiveHeaders = ref(true)
+const headersSaving = ref(false)
+watch(
+  () => mesh.status,
+  (s) => {
+    if (!s) return
+    if (typeof s.announce_block_headers === 'boolean') announceHeaders.value = s.announce_block_headers
+    if (typeof s.receive_block_headers === 'boolean') receiveHeaders.value = s.receive_block_headers
+  },
+  { immediate: true, deep: true }
+)
+async function setAnnounceHeaders(v: boolean) {
+  announceHeaders.value = v
+  headersSaving.value = true
+  try { await mesh.configure({ announce_block_headers: v }) } catch { /* surfaced via store error */ } finally { headersSaving.value = false }
+}
+async function setReceiveHeaders(v: boolean) {
+  receiveHeaders.value = v
+  headersSaving.value = true
+  try { await mesh.configure({ receive_block_headers: v }) } catch { /* surfaced via store error */ } finally { headersSaving.value = false }
+}
+
 const txHexInput = ref('')
 const bolt11Input = ref('')
 const bolt11AmountInput = ref('')
@@ -120,6 +146,22 @@ async function handleRelayLightning() {
           <span class="mesh-block-hash">{{ h.hash.slice(0, 12) }}...{{ h.hash.slice(-8) }}</span>
         </div>
       </div>
+
+      <!-- Header send/receive toggles (issue #28) -->
+      <div class="flex items-center justify-between gap-3 pt-3 mt-2 border-t border-white/10">
+        <div class="min-w-0">
+          <span class="mesh-bitcoin-label">Send headers</span>
+          <small class="mesh-bitcoin-hint">Broadcast new block headers to mesh peers (needs internet)</small>
+        </div>
+        <ToggleSwitch :model-value="announceHeaders" :disabled="headersSaving" @update:model-value="setAnnounceHeaders" />
+      </div>
+      <div class="flex items-center justify-between gap-3 pt-3">
+        <div class="min-w-0">
+          <span class="mesh-bitcoin-label">Receive headers</span>
+          <small class="mesh-bitcoin-hint">Accept block headers relayed by peers</small>
+        </div>
+        <ToggleSwitch :model-value="receiveHeaders" :disabled="headersSaving" @update:model-value="setReceiveHeaders" />
+      </div>
     </div>
 
     <!-- On-Chain / Lightning tabs -->