ci: expire CI build artifacts after a week

The install job uploads node_modules, the turbo cache, and the build
output on every pull request run, which adds up to tens of gigabytes of
storage for data only the downstream jobs in the same run ever read.

Co-Authored-By: claude-opus-5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -33,6 +33,7 @@ jobs:
         with:
           name: node_modules-${{ github.run_id }}
           path: node_modules.tar.gz
+          retention-days: 7
 
       - name: Archive turbo cache
         run: tar -czf turbo-cache.tar.gz .turbo
@@ -41,6 +42,7 @@ jobs:
         with:
           name: turbo-cache-${{ github.run_id }}
           path: turbo-cache.tar.gz
+          retention-days: 7
 
       - name: Archive build artifacts
         run: |
@@ -51,6 +53,7 @@ jobs:
         with:
           name: build-artifacts-${{ github.run_id }}
           path: build-artifacts.tar.gz
+          retention-days: 7
 
   lint:
     runs-on: ubuntu-latest