hub v0.112.0: a floor carries a declared MinAgent past the golden (R-472)

Operator ruling 2026-09-13. Above the vouched golden, a floor saved with a
declared MinAgent is served under the same agent comparison; an undeclared
one is still held beyond the golden. The declaration is stored beside each
floor as FLOOR=MINAGENT so it never carries to a later floor. Both floor
forms require min_agent above the golden (flash floor_needs_min_agent,
nothing stored). The Hosts page and the API log name the source.

Vouch path and R-120 gate untouched. Scenarios A-E tested; red-proofs A
and C in documentation/audits/rulings-r472-r475-2026-09-13/.

documentation/audits/rulings-r472-r475-2026-09-13/rp-hub-A-declared-branch-removed.txt

@@ -0,0 +1,13 @@
+MUTATION in internal/store/store.go:
+  - 	if beyondGolden && d.DeclaredMinAgent != "" {
+		d.MinAgent, d.MinAgentSource = d.DeclaredMinAgent, MinAgentSourceDeclared
+	}
+  + 	_ = MinAgentSourceDeclared
+
+=== RUN   TestDeclaredMinAgent_A_AboveGoldenServedWhenAgentMeetsIt
+    declared_floor_test.go:33: a declared floor above the golden must be SERVED: {Floor: Held:true AgentVersion:0.129.0 RequestedFloor:0.239.0 MinAgent:0.129.0 GoldenVersion:0.236.0 HeldBeyondGolden:true DeclaredMinAgent:0.129.0 MinAgentSource:manifest} (reason "held: floor 0.239.0 is ABOVE the vouched golden 0.236.0, so its agent requirement is unknown — vouch a golden carrying the floor's controller (publish-train rule 1)")
+--- FAIL: TestDeclaredMinAgent_A_AboveGoldenServedWhenAgentMeetsIt (0.02s)
+FAIL
+FAIL	gitea.dooplex.hu/admin/felhom-hub/internal/store	0.027s
+FAIL
+exit=1

documentation/audits/rulings-r472-r475-2026-09-13/rp-hub-C-undeclared-served.txt

@@ -0,0 +1,11 @@
+MUTATION in internal/store/store.go:
+  - 	if beyondGolden && d.MinAgentSource != MinAgentSourceDeclared {
+  + 	if false && beyondGolden && d.MinAgentSource != MinAgentSourceDeclared {
+
+=== RUN   TestDeclaredMinAgent_C_UndeclaredAboveGoldenIsHeldExactlyAsBefore
+    declared_floor_test.go:64: an UNDECLARED floor above the golden must stay held beyond the golden: {Floor:0.239.0 Held:false AgentVersion:0.130.0 RequestedFloor:0.239.0 MinAgent:0.129.0 GoldenVersion:0.236.0 HeldBeyondGolden:false DeclaredMinAgent: MinAgentSource:manifest}
+--- FAIL: TestDeclaredMinAgent_C_UndeclaredAboveGoldenIsHeldExactlyAsBefore (0.02s)
+FAIL
+FAIL	gitea.dooplex.hu/admin/felhom-hub/internal/store	0.031s
+FAIL
+exit=1