fix(ci): unset SODIUM_USE_PKG_CONFIG before cargo builds on all platforms

The libsodium-sys-stable build.rs panics if both SODIUM_LIB_DIR and
SODIUM_USE_PKG_CONFIG are set simultaneously. The runner infrastructure
at 172.0.0.29 has SODIUM_USE_PKG_CONFIG in its container environment
(not traceable to any workflow file or Docker image ENV layer), which
conflicts with the SODIUM_LIB_DIR approach used for cross-compilation.

Explicitly unset SODIUM_USE_PKG_CONFIG in the shell before npm/cargo
runs on all three platforms (linux-amd64, windows-amd64, linux-arm64)
in both release-beta.yml and auto-tag.yml. This is a defensive no-op
when the variable is absent, and a clean fix when it is present.

CHANGELOG.md

@@ -4,6 +4,13 @@ All notable changes to TRCAA are documented here.
 Commit types shown: feat, fix, perf, docs, refactor.
 CI, chore, and build changes are excluded.
 
+## [Unreleased]
+
+### Bug Fixes
+- Register missing updater commands
+- **ci**: Add libsodium to all build environments
+- **ci**: Unset SODIUM_USE_PKG_CONFIG and use SODIUM_LIB_DIR in auto-tag.yml
+
 ## [1.2.3] — 2026-06-13
 
 ### Bug Fixes