fix(ci): enable libsodium pkg-config feature across all platforms

Explicitly adds libsodium-sys-stable dependency with use-pkg-config
feature to ensure builds use system libsodium via pkg-config instead
of attempting vendored builds.

Changes:
- Add direct dependency on libsodium-sys-stable with use-pkg-config feature
- Update Windows build to use pkg-config with cross-compilation support
- Remove manual SODIUM_* env vars that bypass pkg-config

This resolves "libsodium not found via pkg-config or vcpkg" build
failures on Linux and Windows CI targets.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.gitea/workflows/auto-tag.yml

@@ -444,9 +444,8 @@ jobs:
           CARGO_TARGET_X86_64_PC_WINDOWS_GNU_LINKER: x86_64-w64-mingw32-gcc
           OPENSSL_NO_VENDOR: "0"
           OPENSSL_STATIC: "1"
-          SODIUM_LIB_DIR: /usr/x86_64-w64-mingw32/lib
-          SODIUM_STATIC: "1"
-          SODIUM_USE_PKG_CONFIG: "no"
+          PKG_CONFIG_x86_64_pc_windows_gnu: x86_64-w64-mingw32-pkg-config
+          PKG_CONFIG_ALLOW_CROSS: "1"
         run: |
           npm ci --legacy-peer-deps
           CI=true npx tauri build --target x86_64-pc-windows-gnu

src-tauri/Cargo.lock

@@ -6545,6 +6545,7 @@ dependencies = [
  "http 1.4.1",
  "infer 0.15.0",
  "lazy_static",
+ "libsodium-sys-stable",
  "lopdf",
  "mockito",
  "portable-pty",

src-tauri/Cargo.toml

@@ -59,6 +59,7 @@ http = "1.4"
 flate2 = { version = "1", features = ["rust_backend"] }
 serde_yaml = "0.9"
 portable-pty = "0.8"
+libsodium-sys-stable = { version = "1.24", features = ["use-pkg-config"] }