Pin libsodium to 1.10021.11: 1.10021.12 no longer links with LibSSH

WireGuard brings libsodium in unpinned. 1.10021.12 defines
crypto_sign_ed25519_open, as LibSSH-ESP32 does: a clean build failed with
a multiple definition. A cached build kept linking, which hid it.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162FokPdvY2KsS4NBfwyWPk

platformio.ini

@@ -26,6 +26,8 @@ lib_deps =
     jgromes/RadioLib @ 7.8.1
     esphome/wireguard @ 0.4.8
     ewpa/LibSSH-ESP32 @ 5.10.0
+    ; WireGuard brings libsodium in; 1.10021.12 defines crypto_sign_ed25519_open as LibSSH does, and the two do not link
+    esphome/libsodium @ 1.10021.11
 test_ignore = *
 ; Smaller TLS buffers (M2): the framework is rebuilt with these settings (pioarduino "hybrid
 ; compile"). Receive stays 16 KB (servers send full TLS records); send drops to 4 KB (IRC lines are