fix(ci): properly use cargo cache across jobs

- Remove destructive cleanup step that deleted cached artifacts
- Add shared-key 'platform-build' to share cache between jobs
- Build job saves cache, other jobs read from it

This should significantly speed up CI by reusing compiled dependencies.

Author: echobt

.github/workflows/ci.yml

@@ -35,16 +35,11 @@ jobs:
         uses: Swatinem/rust-cache@v2
         with:
           cache-on-failure: true
+          shared-key: "platform-build"
 
       - name: Build
         run: cargo build --release
 
-      - name: Cleanup before cache
-        run: |
-          rm -rf target/release/.fingerprint target/release/build target/release/deps target/release/examples target/release/incremental
-          find target -name "*.d" -delete
-          df -h
-
   test:
     name: Test
     runs-on: ubuntu-latest
@@ -70,7 +65,7 @@ jobs:
       - name: Cache cargo
         uses: Swatinem/rust-cache@v2
         with:
-          cache-on-failure: true
+          shared-key: "platform-build"
           save-if: false
 
       - name: Run tests with coverage
@@ -117,7 +112,7 @@ jobs:
       - name: Cache cargo
         uses: Swatinem/rust-cache@v2
         with:
-          cache-on-failure: true
+          shared-key: "platform-build"
           save-if: false
 
       - name: Run clippy
@@ -196,6 +191,7 @@ jobs:
       - name: Cache cargo
         uses: Swatinem/rust-cache@v2
         with:
+          shared-key: "platform-build"
           save-if: false
 
       - name: Build release binaries