fix(mesh): Reticulum garbage-text + reconnect churn + signal bars + node naming/HTTPS

- reticulum.rs: send_text_msg was lossy-UTF8-mangling binary CBOR control
  envelopes (ReadReceipt etc.) before sending as LXMF text; base64-encode
  with a marker instead, decoded losslessly on receive.
- typed_messages.rs: mesh.send-read-receipt fired automatically on every
  chat view with no is_archy_peer gate, so viewing a message from a stock
  (non-archy) LXMF peer auto-sent it an undecodable control envelope,
  surfacing as garbage text right after whatever it just sent. Now a no-op
  for non-archy peers.
- mesh/listener/mod.rs: RX_STALL_TIMEOUT was 300s and forced a full
  auto-detect reconnect on any otherwise-healthy but quiet mesh link
  (visible as "Connecting..." flapping); this also wiped Reticulum's
  in-memory peer-address table every cycle, breaking messaging with peers
  who hadn't re-announced in the window. Bumped to 1800s.
- reticulum.rs: persist the peer prefix/dest-hash/display-name table to
  disk so a restart doesn't force every peer back to "Anonymous Peer"
  until they re-announce.
- decode.rs/frames.rs: Meshcore was discarding the SNR its wire format
  carries; wire it onto the peer record. Mesh.vue's signalBars() now falls
  back to SNR-based bars when RSSI is unavailable (always true for
  Meshcore); Reticulum has neither and correctly stays at 0/"no data".
- system/handlers.rs, dispatcher.rs: new system.get-hostname RPC + cert
  regeneration (with a proper SAN) whenever server.set-name changes the
  hostname, so HTTPS doesn't add a mismatch warning on top of the
  self-signed one after a rename.
- AccountInfoSection.vue: surface the mDNS hostname + http/https links in
  Settings (HTTPS needed for mic/camera secure-context features) — never
  forced, both keep working.
- build-auto-installer-iso.sh: ship avahi-daemon so .local names actually
  resolve on the LAN, and give the self-signed cert a real SAN instead of
  a bare CN, both at image-build and install-time-fallback.
- Mesh.vue/MediaLightbox.vue/mesh-styles.css: mic/attach-stack no longer
  closes on a plain hover-past; mesh images open in the shared lightbox
  and have a real download button; lightbox close button moves to
  bottom-center on mobile instead of under the status bar; mesh device
  panel gets the same height/padding as its sibling tabs.

Verified: 108/108 mesh unit tests, deployed + confirmed healthy on
.116/.198/.228 (matching binary hash across all three), live Reticulum
messaging confirmed working end-to-end post-deploy.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

neode-ui/src/components/cloud/MediaLightbox.vue

@@ -416,5 +416,20 @@ onUnmounted(() => {
   .lightbox-nav-next { right: 0.5rem; }
   .lightbox-audio-artwork { width: 8rem; height: 8rem; }
   .lightbox-media-video { border-radius: 0; }
+
+  /* The close button used to sit in the top bar, which lands under the
+     status bar / notch safe area on most phones and is awkward to reach.
+     Detach it from the top bar and pin it bottom-center, under the media,
+     for mobile only — desktop keeps it in the top bar. */
+  .lightbox-topbar { padding-right: 1rem; }
+  .lightbox-topbar .lightbox-btn {
+    position: fixed;
+    top: auto;
+    bottom: calc(env(safe-area-inset-bottom, 0px) + 1rem);
+    left: 50%;
+    right: auto;
+    transform: translateX(-50%);
+    z-index: 20;
+  }
 }
 </style>