feat: LLM router with chat intent and Cyrillic wake-word support

- Add LLMRouter: grammar-constrained LFM call for intent classification
  after stage-0, before classifier cascade. Errors fall through gracefully.
- Add IntentChat: conversational intent with no store side-effect, routed
  through LLM -> phraser chat endpoint.
- Extract slots for Chat: no structured slots, full utterance is payload.
- Extend stage-0 grammars to fire through Cyrillic wake-word spellings
  (Мэйвен/Мейвен/Майвен/etc.) produced by Russian STT model.
- StripWakeToken helper strips leading wake in any script so time/date
  grammars still match when wake is present.
- Add classifier examples for chat utterances (EN + RU).
- Wire LLMRouter into Router.Config; optional, nil-safe.

internal/router/llmrouter_test.go

@@ -0,0 +1,74 @@
+package router
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/kami/maven/internal/llm"
+)
+
+type mockLLM struct{ out string; err error }
+
+func (m mockLLM) Complete(_ context.Context, _ llm.Req) (string, error) { return m.out, m.err }
+
+func TestLLMRouterFactMapping(t *testing.T) {
+	lr := NewLLMRouter(mockLLM{out: `{"intent":"fact","key":"water","value":"выпил"}`})
+	d, ok, err := lr.Route(context.Background(), "я выпил воду", time.Now())
+	if err != nil || !ok {
+		t.Fatalf("ok=%v err=%v", ok, err)
+	}
+	if d.Intent != IntentFact || d.Slots.Key != "water" || !d.Slots.HasKey {
+		t.Fatalf("bad decision %+v", d)
+	}
+}
+
+func TestLLMRouterNoteMapping(t *testing.T) {
+	lr := NewLLMRouter(mockLLM{out: `{"intent":"note","text":"кофе закончился"}`})
+	d, ok, err := lr.Route(context.Background(), "запомни что кофе закончился", time.Now())
+	if err != nil || !ok {
+		t.Fatalf("ok=%v err=%v", ok, err)
+	}
+	if d.Intent != IntentNote || d.Slots.Text != "кофе закончился" {
+		t.Fatalf("bad decision %+v", d)
+	}
+}
+
+func TestLLMRouterBadJSONFallsBack(t *testing.T) {
+	lr := NewLLMRouter(mockLLM{out: `garbage`})
+	_, ok, err := lr.Route(context.Background(), "x", time.Now())
+	if ok || err == nil {
+		t.Fatal("want ok=false, err!=nil on bad json")
+	}
+}
+
+func TestLLMRouterReminderMapping(t *testing.T) {
+	lr := NewLLMRouter(mockLLM{out: `{"intent":"reminder","text":"позвонить маме"}`})
+	d, ok, err := lr.Route(context.Background(), "напомни позвонить маме", time.Now())
+	if err != nil || !ok {
+		t.Fatalf("ok=%v err=%v", ok, err)
+	}
+	if d.Intent != IntentReminder || d.Slots.Text != "позвонить маме" {
+		t.Fatalf("bad decision %+v", d)
+	}
+}
+
+func TestLLMRouterChatFallback(t *testing.T) {
+	lr := NewLLMRouter(mockLLM{out: `{"intent":"unknown"}`})
+	d, ok, err := lr.Route(context.Background(), "как дела?", time.Now())
+	if err != nil || !ok {
+		t.Fatalf("ok=%v err=%v", ok, err)
+	}
+	if d.Intent != IntentChat {
+		t.Fatalf("unknown intent should default to chat, got %s", d.Intent)
+	}
+}
+
+func TestLLMRouterLLMError(t *testing.T) {
+	lr := NewLLMRouter(mockLLM{out: "", err: fmt.Errorf("llm down")})
+	_, ok, err := lr.Route(context.Background(), "x", time.Now())
+	if ok || err == nil {
+		t.Fatal("want ok=false, err!=nil on llm error")
+	}
+}