Delete merge-check.sh, check-nested-modules.sh, the store-tests list and RELEASE-57: the checker runs the build module's steps, nested modules by convention (issue 1294, C7a and C7b)

Makefile

@@ -79,26 +79,6 @@ redis-provisioner-image:
 	@echo
 	@docker image inspect $(REDIS_PROVISIONER_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
 
-# The whole check. Raises a database, runs the repository's own check against it -- merge-check.sh,
-# the very script `mesh/repo-check` runs -- and takes the database down again, including when the
-# check fails, which is why the teardown is not conditional and the script's exit status is the
-# target's.
-#
-# **It calls the script rather than restating it** (novox/hq issue 431): this target used to list its
-# own steps, its formatting step walked vendor/ where the script's does not, and it failed on
-# third-party code no change could fix -- so a developer's check and the gate disagreed, and the steps
-# after formatting never ran through it. The script is the one list of steps; this target only gives it
-# a database (MESH_TEST_POSTGRES, exported above).
-#
-# **Two levels** (issue 895): the unit level, `go test ./...` untagged, timed and held to a bound; and the integration
-# level, `-tags integration`, the tests that start a bus, a store or another process. Each is said with its time.
-#
-# **Packages in parallel, under the race detector, each test on a bus of its own** (internal/testbus),
-# as the script runs them: a bus per test, of the release the mesh runs, makes the suite the same in any
-# order, and the timeout bounds a hang to a failure with a stack, never a stalled gate.
-check: postgres
-	@sh merge-check.sh ; status=$$? ; docker rm -f -v $(PG_CONTAINER) >/dev/null 2>&1 || true ; exit $$status
-
 # The unit level alone (untagged: no bus, no store, no other process), which a developer runs continuously. The tests
 # that need a bus or the store carry `//go:build integration` and run in `check`, not here; without a database the
 # store's tests would skip rather than fail anyway.
@@ -108,8 +88,7 @@ test:
 vet:
 	go vet ./...
 
-# Quick steps for a developer, not part of `check`. The directories gofmt reads must be the ones
-# merge-check.sh lists, never `.`, which walks vendor/ (novox/hq issue 431).
+# A quick step for a developer: the checker runs the build module's own formatting and vet (ADR 0501 §5, D7).
 fmt:
 	@unformatted=$$(gofmt -l cmd internal examples) ; \
 	if [ -n "$$unformatted" ] ; then echo "not gofmt'd:" ; echo "$$unformatted" ; exit 1 ; fi