Update MeshCore base to v1.16.0; add sig/air/coin; ship 139 boards

- Bump vendor/MeshCore pin 910b1bee -> bbb58cce (upstream v1.16.0,
  272 commits) and rebase the 14-patch bot queue onto it; one trivial
  conflict in the MyMesh constructor.
- New patch 15: sig/air/coin commands plus registry-derived help and
  cmd listings ('cmd diag' for the diagnostic set). BOT_PREFS_VERSION
  bumped to 7. Host tests cover the new commands and assert every
  discoverable registry entry appears in a listing.
- Re-include six boards fixed upstream (Pico W, RAK 11310, Waveshare
  RP2040 LoRa, Xiao RP2040, Nibble USB+BLE) after local test builds;
  remaining exclusions are BLE flash-size only.
- Fix release env enumeration to strip CR line endings so envs in CRLF
  variant files (Minewsemi ME25LS01, Wio WM1110, Nibble) are counted
  and built; verified all three build locally.
- Refresh README/CHANGELOG/RELEASE/CONTRIBUTING for the new base and
  command set.

Verified: host tests, safety checks, 4 representative builds, and 9
additional env builds all pass; the 15-patch queue applies cleanly to
pristine bbb58cce.

patches/meshcore/0003-Allow-prefixless-firmware-bot-DMs.patch

@@ -1,7 +1,7 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: cj-vana <cj@depth23.online>
 Date: Fri, 15 May 2026 20:09:58 -0600
-Subject: [PATCH 03/14] Allow prefixless firmware bot DMs
+Subject: [PATCH 03/15] Allow prefixless firmware bot DMs
 
 ---
  examples/companion_radio/BotPolicy.cpp | 2 +-