Compile the test targets CI skips before trusting a merged integration branch

Two feature branches each added let ok5 = await ... in the same long Swift test function; git merged them with no conflict and the app CI stayed green because it only builds the app, so the harness had never compiled on any integration commit (invalid redeclaration). A second branch's package tests also never compiled (a mutating call inside Swift Testing's #require gives "'$0' is immutable"; bind the result to a local first, then #require it). When auditing an integration, build every test target and harness the CI does not, and rerun each failure once with a cleaned environment: on macOS an exact-path compare in a shell test fails under the default TMPDIR because /var is a symlink to /private/var and the code under test canonicalises paths, so compare against $(cd "$T" && pwd -P).