feat(llm): full multi-tier S/A/B/C/D with routing + pricing

Estende ModelTier a 5 livelli (S/A/B/C/D) con routing automatico:
S/A/B via Anthropic SDK, C/D via OpenRouter (OpenAI SDK). Aggiunge
prezzi per tier S (Opus), A (Sonnet placeholder) e D (Llama). Refactor
LLMClient.complete con dispatch tramite tier_models map e helper
_call_anthropic / _call_openrouter. Settings esposte per tutti e 5
i modelli env-configurabili.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit/test_genome_hypothesis.py

@@ -48,3 +48,22 @@ def test_genome_id_is_deterministic_on_content():
         top_p=0.9, model_tier=ModelTier.C, lookback_window=100, cognitive_style="x",
     )
     assert g1.id == g2.id
+
+
+def test_genome_all_tiers_serde_roundtrip():
+    """Tutti i 5 tier (S, A, B, C, D) sopravvivono a to_dict/from_dict."""
+    for tier in (ModelTier.S, ModelTier.A, ModelTier.B, ModelTier.C, ModelTier.D):
+        g = HypothesisAgentGenome(
+            system_prompt="prompt",
+            feature_access=["close"],
+            temperature=0.7,
+            top_p=0.9,
+            model_tier=tier,
+            lookback_window=128,
+            cognitive_style="generic",
+        )
+        payload = g.to_dict()
+        assert payload["model_tier"] == tier.value
+        g2 = HypothesisAgentGenome.from_dict(payload)
+        assert g2.model_tier == tier
+        assert g2.id == g.id