ci: remove save-always, remove old vcpkg cache key, flush vcpkg caches

.cargo/config.toml

@@ -1,6 +1,16 @@
 [target.'cfg(target_os = "emscripten")']
 rustflags = [
+    # Stack size is required for this project, it will crash otherwise.
     "-C", "link-args=-sASYNCIFY=1 -sASYNCIFY_STACK_SIZE=8192 -sALLOW_MEMORY_GROWTH=1",
     "-C", "link-args=-sUSE_SDL=2 -sUSE_SDL_IMAGE=2 -sUSE_SDL_MIXER=2 -sUSE_OGG=1 -sUSE_SDL_GFX=2 -sUSE_SDL_TTF=2 -sSDL2_IMAGE_FORMATS=['png']",
     "-C", "link-args=--preload-file assets/game/",
 ]
+
+[target.'cfg(target_os = "linux")']
+rustflags = [
+    # Manually link zlib.
+    # The `sdl2` crate's build script uses `libpng`, which requires `zlib`.
+    # By adding `-lz` here, we ensure it's passed to the linker after `libpng`,
+    # which is required for the linker to correctly resolve symbols.
+    "-C", "link-arg=-lz",
+]

.github/workflows/build.yaml

@@ -44,18 +44,16 @@ jobs:
       - name: Cache vcpkg
         uses: actions/cache@v4
         with:
-          save-always: true # deprecated
           path: target/vcpkg
-          key: vcpkg-${{ runner.os }}-${{ matrix.target }}-${{ hashFiles('Cargo.toml', 'Cargo.lock') }}
+          key: A-vcpkg-${{ runner.os }}-${{ matrix.target }}-${{ hashFiles('Cargo.toml', 'Cargo.lock') }}
           restore-keys: |
-            ${{ runner.os }}-vcpkg
+            A-vcpkg-${{ runner.os }}-${{ matrix.target }}-
-            vcpkg-${{ runner.os }}-${{ matrix.target }}-
 
       - name: Vcpkg Linux Dependencies
         if: runner.os == 'Linux'
         run: |
           sudo apt-get update
-          sudo apt-get install -y build-essential gettext libltdl-dev zlib1g-dev
+          sudo apt-get install -y libltdl-dev
 
       - name: Vcpkg
         run: |