Word nudges from templates by default, model optional

DEPRECATION, flagged not asked: LLM-phrased nudges are no longer the default.
LLMPhraser.PhraseNudge now returns a hand-written Russian template. The model
still phrases chat, queries and reminders — only nudges moved.

Why: measured over many runs, Qwen3.5-0.8B wrote formal "вы" and plural
imperatives, used masculine self-reference, and invented facts and units
(90-95 seconds to boil an egg). A nudge is five words of known content, so
generation buys nothing and risks the persona every time. Templates score
15/15 on the nudge fixture, the model 11-13/15.

Nothing is deleted: the prompt, the fallbacks and the whole LLM nudge path
stay. Set phraser.llm_nudges = true in deploy/mavend.json to get them back.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CGeSZxh1DCtRxmFVSYVGvJ

internal/phraser/nudge_templates_test.go

@@ -158,6 +158,38 @@ func TestRuSinceWords(t *testing.T) {
 	}
 }
 
+// Templates are the default: a nudge must not reach the model at all.
+func TestLLMPhraserUsesTemplatesByDefault(t *testing.T) {
+	spy := newGrammarSpy(t)
+	p := NewLLMPhraserAt(spy.srv.URL, Config{})
+	pn, err := p.PhraseNudge(context.Background(), cand("water", 200, ""))
+	if err != nil {
+		t.Fatalf("PhraseNudge: %v", err)
+	}
+	if len(spy.grammars) != 0 {
+		t.Errorf("nudge hit the model %d times, want 0", len(spy.grammars))
+	}
+	if !strings.Contains(strings.ToLower(pn.Body), "вод") {
+		t.Errorf("nudge is not the water template: %q", pn.Body)
+	}
+}
+
+// ...and the flag brings the model back.
+func TestLLMNudgesFlagRestoresTheModel(t *testing.T) {
+	spy := newGrammarSpy(t)
+	p := NewLLMPhraserAt(spy.srv.URL, Config{LLMNudges: true})
+	pn, err := p.PhraseNudge(context.Background(), cand("water", 200, ""))
+	if err != nil {
+		t.Fatalf("PhraseNudge: %v", err)
+	}
+	if len(spy.grammars) != 1 {
+		t.Fatalf("nudge hit the model %d times, want 1", len(spy.grammars))
+	}
+	if pn.Body != "ага" {
+		t.Errorf("body = %q, want the model's reply", pn.Body)
+	}
+}
+
 func TestNudgeTemplatesPhraseNudge(t *testing.T) {
 	nt := newTestTemplates(t, 5)
 	pn, err := nt.PhraseNudge(context.Background(), cand("water", 200, ""))