Name the decisions these tests defend, and check the bundle at all

From auditing the decision records: of 28, only 12 were named by any
test, so "which decisions are defended" could not be answered without
reading everything. ADR 0017 says a test names the decision it defends —
that rule was itself unenforced.

Most of the gap was citation, not coverage. Drift detection was tested
in several places without naming ADR 0011; the archive refusal without
naming 0012; forged declarations without naming 0002. Named now, so the
question is answerable by grep.

The bundle was the real gap: nothing tested substrate-first-node.lock at
all. It is what a machine becomes when there is no mesh to ask — the one
declaration applied with nothing to verify it against — and it was
edited by hand and read by nothing but a running host.

Two tests now assert what it carries: exactly postgres, lavinmq and the
control plane. That defends ADR 0028, which removed the object store
from the substrate after it had been a member for months on the strength
of "it cannot grant itself a bucket" — true, and the answer to only half
the test. Nothing counted what the bundle held.

Fault-injected, and the first attempt did not bite: the injection landed
on a comment line, which stripComments discards. Injecting into the
image field fails as it should.

internal/link/messages_test.go

@@ -44,6 +44,11 @@ func TestTheMeshsOwnDeclarationIsApplied(t *testing.T) {
 	}
 }
 
+// Defends novox/hq ADR 0002: everything reaching a node arrives over the broker — and therefore
+// ADR 0004's consequence, that the broker is not trusted to say who is speaking.
+//
+// A transport nobody authenticates per-message would let whatever holds the connection attribute
+// a declaration to any node it liked.
 func TestAForgedDeclarationIsNeverApplied(t *testing.T) {
 	// The check that stands between "the mesh changes this machine" and "anybody does". The host
 	// applies whatever the link delivers, so a forged declaration is the whole machine.