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.

scripts/list-release-companion-envs.sh

@@ -5,18 +5,15 @@ ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 MESHCORE_DIR="${MESHCORE_DIR:-${ROOT_DIR}/vendor/MeshCore}"
 
 is_excluded() {
+  # BLE variants that do not fit on these boards. The RP2040 and Nibble
+  # envs that used to sit here build again as of upstream bbb58cce
+  # (v1.16.0) and were re-included after passing local test builds.
   case "$1" in
     Heltec_v2_companion_radio_ble|\
     LilyGo_TLora_V2_1_1_6_companion_radio_ble|\
-    nibble_screen_connect_companion_radio_ble|\
-    nibble_screen_connect_companion_radio_usb|\
-    PicoW_companion_radio_usb|\
-    RAK_11310_companion_radio_usb|\
     Station_G2_companion_radio_ble|\
     Tbeam_SX1262_companion_radio_ble|\
-    Tbeam_SX1276_companion_radio_ble|\
-    waveshare_rp2040_lora_companion_radio_usb|\
-    Xiao_rp2040_companion_radio_usb)
+    Tbeam_SX1276_companion_radio_ble)
       return 0
       ;;
     *)
@@ -25,7 +22,10 @@ is_excluded() {
   esac
 }
 
+# The sed strips CR so variant files with CRLF line endings (a few exist
+# upstream) match; without it their envs silently vanish from releases.
 grep -rhE '^\[env:' "${MESHCORE_DIR}/variants/" \
+  | sed -e 's/\r$//' \
   | sort -u \
   | grep -E '_companion_radio_(usb|ble)\]$' \
   | sed -e 's/\[env://' -e 's/\]//' \