fix: install autotools build deps before vcpkg on macOS

vcpkg ports (gperf, fontconfig) need autoconf/automake/libtool to
build from source. These are compile-time tools only — they don't
create runtime dylib dependencies.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/build-desktop.yml

@@ -130,6 +130,11 @@ jobs:
         with:
           fetch-depth: 0
 
+      # Build tools required by vcpkg ports (autotools for gperf, fontconfig, etc.)
+      # These are compile-time only — they do NOT create runtime dylib dependencies.
+      - name: Install build tools
+        run: brew install autoconf autoconf-archive automake libtool pkg-config
+
       # Static linking via vcpkg — avoids runtime dependency on Homebrew dylibs.
       # Ref: https://tectonic-typesetting.github.io/book/latest/howto/build-tectonic/
       # Ref: https://learn.microsoft.com/en-us/vcpkg/users/triplets (arm64-osx defaults to static)
@@ -285,6 +290,10 @@ jobs:
         with:
           fetch-depth: 0
 
+      # Build tools required by vcpkg ports (autotools for gperf, fontconfig, etc.)
+      - name: Install build tools
+        run: brew install autoconf autoconf-archive automake libtool pkg-config
+
       # Static linking via vcpkg — same approach as Apple Silicon and Windows.
       - name: Setup vcpkg
         run: |