brain-ci: Unit Tests call build steps removed in #517

[gHashTag]

What fails

#1326 / #1328 fixed the brain-ci health step: tri stress --health now measures 17 probes and scores 100.0/100. The workflow is still red, because every job after the health step either calls something that no longer exists or measures nothing.

Evidence: brain-ci run 37176676345 on #1328 (head 9097fc9):

Job	Result	Why
Unit Tests (basal-ganglia, reticular-formation, locus-coeruleus, intraparietal, hslm)	failure x5	no step named 'test-basal-ganglia' (and the same for each region). #517 (42490a2) removed these build.zig steps while brain-ci.yml kept calling them.
Integration / Stress / CLI Smoke	skipped	needs: Unit Tests
Brain Health Report	failure	aggregator; the jobs above did not succeed
Export Brain Metrics	success	if: always(); its only measuring step, tri stress --metrics, prints stress-test: TODO - not implemented yet and exits 0

What else is wrong behind the unit failure

• src/brain/intraparietal_sulcus.zig does not compile. It is a set of stubs (GF16 = TF3 = f32, PHI = 3.0) around the hslm model.
• hslm moved to gHashTag/trinity-training. test-hslm never existed in build.zig.
• src/brain/stress_test.zig does not compile: it reads registry.claims, but the registry was later sharded into 16 maps.
• The Stress job pipes zig build test-brain-stress through | tee without pipefail, so a failed build exits 0.
• The Stress job greps a Score: line that the test binary never prints. || echo "0" turns the missing line into 0, which is then compared with a 270/300 threshold that nothing produces.
• The Stress PR comment hard-codes a 100/100 table for every region.
• CLI Smoke calls tri task stats, tri task list and tri event stats with || true, plus tri stress --scan. All four print TODO - not implemented yet and exit 0.
• The health job's "Record Health Snapshot" step runs tri stress --record (a no-op) and then writes "Health snapshot recorded to Hippocampus" to the job summary unconditionally.
• The Brain Health Report prints FAIL for a skipped job.
• The weekly artifact name contains $(date ...). That is never expanded, because with: is not a shell.

Expected

Every brain-ci job either runs a real test and gates on its result, or is removed with the reason written in the workflow. Following #957 / #1328, a missing measurement is reported as NOT MEASURED, never as 0.