ci: create the zig fetch tmp dir the package fetcher assumes

.gitea/workflows/ci.yml

@@ -22,6 +22,14 @@ jobs:
         with:
           version: ${{ env.ZIG_VERSION }}
 
+      # zig 0.16.0's package fetcher creates tmp/<hex>.zip inside the global
+      # cache without creating tmp/ first (src/Package/Fetch.zig:1499), and
+      # setup-zig's restored cache never contains tmp/. Without this, every
+      # dependency fetch dies with "failed to create temporary zip file:
+      # FileNotFound" before any network I/O.
+      - name: Create the fetch temp dir zig assumes
+        run: mkdir -p "${ZIG_GLOBAL_CACHE_DIR:?}/tmp"
+
       - name: Run test suite (unit + hermetic loopback integration)
         run: zig build test -Dintegration
 
@@ -36,6 +44,14 @@ jobs:
         with:
           version: ${{ env.ZIG_VERSION }}
 
+      # zig 0.16.0's package fetcher creates tmp/<hex>.zip inside the global
+      # cache without creating tmp/ first (src/Package/Fetch.zig:1499), and
+      # setup-zig's restored cache never contains tmp/. Without this, every
+      # dependency fetch dies with "failed to create temporary zip file:
+      # FileNotFound" before any network I/O.
+      - name: Create the fetch temp dir zig assumes
+        run: mkdir -p "${ZIG_GLOBAL_CACHE_DIR:?}/tmp"
+
       # qemu-user, not qemu-user-static: Zig execs the bare `qemu-aarch64`
       # name, and the -static package only ships `qemu-aarch64-static`.
       - name: Install qemu-user
@@ -94,6 +110,14 @@ jobs:
         with:
           version: ${{ env.ZIG_VERSION }}
 
+      # zig 0.16.0's package fetcher creates tmp/<hex>.zip inside the global
+      # cache without creating tmp/ first (src/Package/Fetch.zig:1499), and
+      # setup-zig's restored cache never contains tmp/. Without this, every
+      # dependency fetch dies with "failed to create temporary zip file:
+      # FileNotFound" before any network I/O.
+      - name: Create the fetch temp dir zig assumes
+        run: mkdir -p "${ZIG_GLOBAL_CACHE_DIR:?}/tmp"
+
       - name: Set up Node
         uses: actions/setup-node@v4
         with:
@@ -197,6 +221,14 @@ jobs:
         with:
           version: ${{ env.ZIG_VERSION }}
 
+      # zig 0.16.0's package fetcher creates tmp/<hex>.zip inside the global
+      # cache without creating tmp/ first (src/Package/Fetch.zig:1499), and
+      # setup-zig's restored cache never contains tmp/. Without this, every
+      # dependency fetch dies with "failed to create temporary zip file:
+      # FileNotFound" before any network I/O.
+      - name: Create the fetch temp dir zig assumes
+        run: mkdir -p "${ZIG_GLOBAL_CACHE_DIR:?}/tmp"
+
       - name: Set up Node
         uses: actions/setup-node@v4
         with: