Harden semantic boundaries and repair dialogue state

Replace nearest-neighbour personal routing with a frozen class-balanced linear head measured on historical, stratified, cross-validation, holdout, and fresh challenge gates (V-702). Close the four repair handoff holes, preserve nested clarification flows, and route Russian possession statements through structural grammar rather than lexical exceptions (V-573). Owner explicitly requested direct commits to master.

internal/router/eval/claims_test.go

@@ -53,20 +53,17 @@ func TestStage0Contention(t *testing.T) {
 	}
 }
 
-// matchingGrammars — every grammar whose pattern matches AND whose Build
-// accepts, in the daemon's order. Route stops at the first; this does not.
+// matchingGrammars — every regexp or structural grammar that accepts, in the
+// daemon's order. Route stops at the first; this does not.
 func matchingGrammars(grammars []router.Grammar, utterance string) []string {
 	stripped, hadWake := router.StripWakeToken(utterance)
 	var out []string
 	for _, g := range grammars {
-		m := g.Pattern.FindStringSubmatch(utterance)
-		if m == nil && hadWake {
-			m = g.Pattern.FindStringSubmatch(stripped)
+		_, matched, ok := g.Evaluate(utterance)
+		if !matched && hadWake {
+			_, matched, ok = g.Evaluate(stripped)
 		}
-		if m == nil {
-			continue
-		}
-		if _, ok := g.Build(m); !ok {
+		if !matched || !ok {
 			continue
 		}
 		out = append(out, g.Name)