Persist Zig build caches in CI

.gitea/workflows/build-and-release.yml

@@ -1,11 +1,19 @@
 name: Build and Release
 
 on:
+  pull_request:
+    branches:
+      - main
   push:
     branches:
       - main
     tags:
       - 'v*'
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 permissions:
   contents: write
@@ -14,6 +22,9 @@ jobs:
   build:
     name: Build executables
     runs-on: ubuntu-latest
+    env:
+      ZIG_LOCAL_CACHE_DIR: /ci-cache/zig-chess/0.16.0/linux-amd64/local
+      ZIG_GLOBAL_CACHE_DIR: /ci-cache/zig-chess/0.16.0/linux-amd64/global
 
     steps:
       - name: Checkout
@@ -34,17 +45,21 @@ jobs:
           zig version
           glslc --version
 
+      - name: Prepare persistent Zig caches
+        run: |
+          mkdir -p "$ZIG_LOCAL_CACHE_DIR" "$ZIG_GLOBAL_CACHE_DIR"
+
       - name: Build GUI executable
         run: |
           zig build \
-            --cache-dir /tmp/zig-chess-cache \
-            --global-cache-dir /tmp/zig-global-cache
+            --cache-dir "$ZIG_LOCAL_CACHE_DIR" \
+            --global-cache-dir "$ZIG_GLOBAL_CACHE_DIR"
 
       - name: Build magic generator executable
         run: |
           zig build magic-numbers \
-            --cache-dir /tmp/zig-chess-cache \
-            --global-cache-dir /tmp/zig-global-cache
+            --cache-dir "$ZIG_LOCAL_CACHE_DIR" \
+            --global-cache-dir "$ZIG_GLOBAL_CACHE_DIR"
 
       - name: Package executables
         run: |