ci: Give each matrix leg its own ccache key

.github/actions/verify-setup/action.yml

@@ -14,6 +14,11 @@ inputs:
   bender-version:
     description: Bender release to install
     default: '0.32.1'
+  ccache-key:
+    description: >
+      Distinguishes this job's ccache from its siblings. Matrix legs share a job
+      id, so a shared key makes them race and all but one fail to save.
+    default: shared
 runs:
   using: composite
   steps:
@@ -55,10 +60,9 @@ runs:
       uses: actions/cache@v4
       with:
         path: ~/.cache/ccache
-        key: ccache-${{ github.job }}-${{ github.sha }}
+        key: ccache-${{ inputs.ccache-key }}-${{ github.sha }}
         restore-keys: |
-          ccache-${{ github.job }}-
-          ccache-
+          ccache-${{ inputs.ccache-key }}-
 
     - if: inputs.verilator == 'true'
       shell: bash

.github/workflows/verify.yml

@@ -53,6 +53,7 @@ jobs:
         uses: ./.github/actions/verify-setup
         with:
           verilator: 'true'
+          ccache-key: elab-${{ matrix.id }}
       -
         name: Generate RTL
         run: uv run --locked make idma_hw_all
@@ -149,6 +150,7 @@ jobs:
         uses: ./.github/actions/verify-setup
         with:
           verilator: 'true'
+          ccache-key: sim-${{ matrix.suite }}
       -
         name: Generate RTL
         run: uv run --locked make idma_hw_all