docs(eliminate-frontend-makefile): task 3.5 - verified regression suite parity

Pure verification, no code changes. Deployed a live single-node
cluster and ran tests/regression/run.sh against a Meson-built xcecli
binary, then again via the still-present Makefile path -- both
produced identical 28 passed/1 failed/1 skipped results. Reviewer
independently reproduced this three times and traced the one
pre-existing failure (jobs submit's job-ID format regex) through
source and git history to a 2026-05-07 commit, four months before
this spec existed -- logged as bug-1765 (not fixed, out of scope).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XYdtrEWWZfKRRGED7raEYg

.kiro/specs/eliminate-frontend-makefile/tasks.md

@@ -53,7 +53,7 @@
   - _Boundary: test_ha_bootstrap.c, test_ha_ctrlhello.c, apiserver/cmd/main.go, xcecli/cmd/main.go_
   - _Depends: 1.1, 2_
 
-- [ ] 3.5 (P) Verify the regression suite runs against a Meson-built binary with parity to the pre-migration baseline
+- [x] 3.5 (P) Verify the regression suite runs against a Meson-built binary with parity to the pre-migration baseline
   - Run `tests/regression/run.sh` directly (`XCE=<meson-built xcecli path> URL=<live apiserver>`) against a live apiserver built via `/xce-build apiserver`
   - Observable: the run reports the same PASS/FAIL/SKIP counts as the documented pre-migration `make test-integration` baseline, using no Makefile-built artifact
   - _Requirements: 4.1, 4.2, 4.3_