Implement LLM-WP-0007: Kimi K3 default and EUR spend reporting

Add moonshotai/kimi-k3 as OpenRouter basemodel default after live smoke,
USD→EUR cost conversion, append-only usage ledger, and CLI run/cost/spend
week commands with token and euro reporting.

tests/test_costs.py

@@ -10,12 +10,16 @@ def test_known_model_cost_matches_lefevre_smoke_budget():
     assert estimate.cost_source == "rate_table:openai/gpt-4o-mini"
     assert estimate.cost_usd == pytest.approx(0.0087)
     assert estimate.cost_usd == pytest.approx(0.009, rel=0.2)
+    assert estimate.cost_eur is not None
+    assert estimate.fx_source is not None
 
 
 def test_unknown_model_returns_unknown_without_zeroing_cost():
     estimate = estimate_cost("unknown/model", 100, 50)
 
-    assert estimate == CostEstimate(cost_usd=None, cost_source="unknown")
+    assert estimate.cost_usd is None
+    assert estimate.cost_eur is None
+    assert estimate.cost_source == "unknown"
 
 
 def test_registry_override_controls_estimate():
@@ -29,21 +33,40 @@ def test_registry_override_controls_estimate():
         }
     )
 
-    estimate = estimate_cost("vendor/model", 1_000, 500, registry=registry)
+    estimate = estimate_cost("vendor/model", 1_000, 500, registry=registry, fx=1.0)
 
     assert estimate.cost_usd == pytest.approx(2.0)
     assert estimate.prompt_cost_usd == pytest.approx(1.0)
     assert estimate.completion_cost_usd == pytest.approx(1.0)
+    assert estimate.cost_eur == pytest.approx(2.0)
 
 
 def test_zero_tokens_are_valid_and_cost_zero_for_known_model():
-    estimate = CostModel().estimate_cost("openai/gpt-4o-mini", 0, 0)
+    estimate = CostModel(fx=1.0).estimate_cost("openai/gpt-4o-mini", 0, 0)
 
     assert estimate.cost_usd == 0
     assert estimate.prompt_cost_usd == 0
     assert estimate.completion_cost_usd == 0
+    assert estimate.cost_eur == 0
 
 
 def test_negative_tokens_are_rejected():
     with pytest.raises(ValueError, match="prompt_tokens"):
         estimate_cost("openai/gpt-4o-mini", -1, 0)
+
+
+def test_kimi_k3_rate_and_eur_conversion():
+    estimate = estimate_cost("moonshotai/kimi-k3", 1_000, 1_000, fx=0.92)
+
+    # $0.003 + $0.015 = $0.018; ×0.92 = €0.01656
+    assert estimate.cost_usd == pytest.approx(0.018)
+    assert estimate.cost_eur == pytest.approx(0.01656)
+    assert estimate.cost_source == "rate_table:moonshotai/kimi-k3"
+
+
+def test_apply_fx_false_skips_eur():
+    estimate = estimate_cost("moonshotai/kimi-k3", 100, 0, apply_fx=False)
+
+    assert estimate.cost_usd is not None
+    assert estimate.cost_eur is None
+    assert estimate.fx_source is None