Simplify: cache rustup toolchains, skip rust install on cache hit

.gitea/workflows/rust-cache-test.yml

@@ -1,4 +1,4 @@
-name: Rust Build Cache Test
+name: Rust Build
 
 on:
   push:
@@ -17,54 +17,32 @@ jobs:
       - name: Checkout code
         uses: https://gitea.com/actions/checkout@v4
 
-      - name: Install Rust
-        run: |
-          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable
-          source "$HOME/.cargo/env"
-
       - name: Get Cargo lock hash
         id: hash
         run: |
-          source "$HOME/.cargo/env"
           echo "hash=$(cat Cargo.lock Cargo.toml | sha256sum | cut -d' ' -f1)" >> $GITHUB_OUTPUT
 
-      - name: Cache cargo
+      - name: Cache cargo + rustup
+        id: cache
         uses: https://gitea.com/actions/cache@v3
         with:
           path: |
             ~/.cargo/registry
             ~/.cargo/git
+            ~/.rustup/toolchains
+            ~/.rustup/settings.toml
             target
           key: rust-${{ runner.os }}-${{ steps.hash.outputs.hash }}
           restore-keys: |
             rust-${{ runner.os }}-
 
-      - name: Show cache info (before build)
+      - name: Setup Rust
+        if: steps.cache.outputs.cache-hit != 'true'
         run: |
-          source "$HOME/.cargo/env"
-          echo "=== Cache Key ==="
-          echo "rust-${{ runner.os }}-${{ steps.hash.outputs.hash }}"
-          echo ""
-          echo "=== Cargo cache directories (before build) ==="
-          du -sh ~/.cargo/registry ~/.cargo/git target 2>/dev/null || echo "Dirs not yet present"
-          echo ""
-          echo "=== Cargo/Rust versions ==="
-          cargo --version
-          rustc --version
+          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable
 
       - name: Build
-        run: |
-          source "$HOME/.cargo/env"
-          cargo build --verbose
+        run: cargo build --verbose
 
       - name: Run
-        run: |
-          source "$HOME/.cargo/env"
-          cargo run
-
-      - name: Check cache after build
-        run: |
-          echo "=== After build ==="
-          echo "~/.cargo/registry: $(du -sh ~/.cargo/registry 2>/dev/null | cut -f1)"
-          echo "~/.cargo/git: $(du -sh ~/.cargo/git 2>/dev/null | cut -f1)"
-          echo "target: $(du -sh target 2>/dev/null | cut -f1)"
+        run: cargo run