fix(ci): save build logs to PVC for post-mortem debugging

Pipe clippy and test output to /cargo-target/*.log via tee so errors
are readable after pod GC. Fixes blind CI failures.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infra/k8s/argo/ci-pipeline-template.yaml

@@ -357,17 +357,16 @@ spec:
             done
 
             echo "=== Running clippy (lib targets) ==="
-            cargo clippy --workspace --lib -- -D warnings
+            cargo clippy --workspace --lib -- -D warnings 2>&1 | tee /cargo-target/clippy.log
 
             echo "=== Running tests (lib only, no integration) ==="
             set +e
-            cargo test --workspace --lib > /tmp/test-output.log 2>&1
+            cargo test --workspace --lib 2>&1 | tee /cargo-target/test-output.log
             TEST_EXIT=$?
             set -e
-            cat /tmp/test-output.log
             if [ "$TEST_EXIT" -ne 0 ]; then
               echo "=== TEST FAILURES ==="
-              grep -A5 'FAILED\|panicked\|test result: FAILED' /tmp/test-output.log || true
+              grep -A5 'FAILED\|panicked\|test result: FAILED\|error\[' /cargo-target/test-output.log || true
               exit "$TEST_EXIT"
             fi