router: Router.Route consumes NormalizedInput directly (slice 11)

Change Route from (ctx, utterance string, now) to (ctx, input NormalizedInput, now).
The ingress-constructed NormalizedInput now reaches the cascade intact — no
reconstruction downstream. TryFastPath receives the same input, not a rebuilt one.
All callers (production, eval framework, tests) updated to construct NormalizedInput.

internal/router/eval/eval.go

@@ -103,17 +103,17 @@ func (f Fixture) Now() (time.Time, error) {
 // Router — the one thing a route decider must do to be scorable. *router.Router
 // satisfies it directly; an LLM-only path wraps its Route in RouterFunc.
 type Router interface {
-	Route(ctx context.Context, utterance string, now time.Time) (router.Decision, error)
+	Route(ctx context.Context, input router.NormalizedInput, now time.Time) (router.Decision, error)
 }
 
 // RouterFunc adapts a bare function to Router — for scoring a single stage
 // (e.g. *router.LLMRouter, whose Route returns an extra ok bool) without
 // standing up the whole cascade.
-type RouterFunc func(ctx context.Context, utterance string, now time.Time) (router.Decision, error)
+type RouterFunc func(ctx context.Context, input router.NormalizedInput, now time.Time) (router.Decision, error)
 
 // Route implements Router.
-func (f RouterFunc) Route(ctx context.Context, utterance string, now time.Time) (router.Decision, error) {
-	return f(ctx, utterance, now)
+func (f RouterFunc) Route(ctx context.Context, input router.NormalizedInput, now time.Time) (router.Decision, error) {
+	return f(ctx, input, now)
 }
 
 // Outcome — one scored case. Reasons is empty exactly when Pass is true.
@@ -231,7 +231,7 @@ func Score(ctx context.Context, name string, r Router, f Fixture) (Report, error
 
 	for _, c := range f.Cases {
 		start := time.Now()
-		d, err := r.Route(ctx, c.Utterance, now)
+		d, err := r.Route(ctx, router.NormalizedInput{Text: c.Utterance}, now)
 		o := Outcome{Case: c, Decision: d, Err: err, Latency: time.Since(start)}
 		lat = append(lat, o.Latency)