fix: use shell hashing instead of hashFiles() which returns empty on Gitea Actions

.gitea/actions/rust-cache/action.yml

@@ -16,6 +16,17 @@ outputs:
 runs:
   using: composite
   steps:
+    # Gitea Actions does not have Cargo.lock by default (cargo generates it on first build),
+    # and hashFiles() globs don't work reliably here. Use shell hashing instead.
+    - name: Compute cache key
+      id: cache-key
+      shell: bash
+      run: |
+        # Hash both files; if Cargo.lock doesn't exist yet, only Cargo.toml is hashed
+        HASH=$(cat Cargo.toml Cargo.lock 2>/dev/null | sha256sum | cut -d' ' -f1)
+        echo "hash=$HASH" >> $GITHUB_OUTPUT
+        echo "fingerprint=$HASH" >> $GITHUB_ENV
+
     - name: Cache cargo + rustup
       id: cache
       uses: https://gitea.com/actions/cache@v3
@@ -26,10 +37,8 @@ runs:
           ~/.rustup/toolchains
           ~/.rustup/settings.toml
           target
-        key: rust-linux-${{ hashFiles('**/Cargo.lock') }}-${{ hashFiles('**/Cargo.toml') }}
-        restore-keys: |
-          rust-linux-${{ hashFiles('**/Cargo.lock') }}-
-          rust-linux-
+        key: rust-linux-${{ steps.cache-key.outputs.hash }}
+        restore-keys: rust-linux-
 
     - name: Setup Rust
       shell: bash