Add cancel-in-progress concurrency to reusable CI (#38)

Superseded CI runs on the same ref keep consuming runners and delay
feedback on the latest push. Add a job-level concurrency group keyed
on github.workflow and github.ref so a new push cancels the in-flight
CI run for that branch.

Concurrency is set at the job level rather than the workflow level
because these are workflow_call reusable workflows: workflow-level
concurrency would resolve github.workflow against the caller's context,
collapsing unrelated callers into one group. cd-* deploy workflows are
intentionally left untouched to avoid cancelling in-flight deploys.

.github/workflows/ci-dotnet.yaml

@@ -24,6 +24,9 @@ jobs:
   ci:
     runs-on: ubuntu-latest
     timeout-minutes: 20
+    concurrency:
+      group: ci-${{ github.workflow }}-${{ github.ref }}
+      cancel-in-progress: true
     defaults:
       run:
         working-directory: ${{ inputs.working-directory }}

.github/workflows/ci-python-sam.yaml

@@ -48,6 +48,9 @@ jobs:
   ci:
     runs-on: ubuntu-latest
     timeout-minutes: 10
+    concurrency:
+      group: ci-${{ github.workflow }}-${{ github.ref }}
+      cancel-in-progress: true
     steps:
       - uses: actions/checkout@v6
 

.github/workflows/ci-typescript-cdk.yaml

@@ -60,6 +60,9 @@ jobs:
   ci:
     runs-on: ubuntu-latest
     timeout-minutes: 30
+    concurrency:
+      group: ci-${{ github.workflow }}-${{ github.ref }}
+      cancel-in-progress: true
     steps:
       - uses: actions/checkout@v6