feat: WP-0003 — RoutingPolicy (FR-2) and HTTP serve mode (FR-1)

FR-2 RoutingPolicy:
- RoutingPolicy + RoutingRule dataclasses in llm_connect/routing.py
- resolve(task_type, estimated_cost_per_1k=None) with cost-cap fallback
- Exported from llm_connect.__init__; contract doc at contracts/functional/routing-policy.md
- 11 tests covering rule match, cost-cap, fallback, unknown type, no-match

FR-1 HTTP serve mode:
- LLMServer in llm_connect/server.py (stdlib http.server, zero extra deps)
- POST /execute + GET /health; CLI via python -m llm_connect.server
- [server] optional-dep group added to pyproject.toml
- Contract doc at contracts/functional/server.md
- 9 tests: health, round-trip, 400/404/500 errors, config forwarding
- Added "mock" provider to factory for CLI default

All 101 tests pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_routing.py

@@ -0,0 +1,91 @@
+"""
+Tests for RoutingPolicy (FR-2).
+"""
+
+import pytest
+
+from llm_connect.routing import RoutingPolicy, RoutingRule
+from llm_connect.adapter import MockLLMAdapter
+
+
+class TestRoutingPolicy:
+    def _adapters(self, n: int = 3):
+        return [MockLLMAdapter(mock_response=f"resp-{i}") for i in range(n)]
+
+    def test_rule_match_returns_prefer(self):
+        prefer, *_ = self._adapters()
+        policy = RoutingPolicy(rules=[RoutingRule("triage", prefer=prefer)])
+        assert policy.resolve("triage") is prefer
+
+    def test_first_matching_rule_wins(self):
+        a, b = self._adapters(2)
+        policy = RoutingPolicy(rules=[
+            RoutingRule("triage", prefer=a),
+            RoutingRule("triage", prefer=b),
+        ])
+        assert policy.resolve("triage") is a
+
+    def test_cost_cap_within_limit_returns_prefer(self):
+        prefer, fallback = self._adapters(2)
+        policy = RoutingPolicy(rules=[
+            RoutingRule("triage", prefer=prefer, max_cost_per_1k=1.0, fallback=fallback)
+        ])
+        assert policy.resolve("triage", estimated_cost_per_1k=0.5) is prefer
+
+    def test_cost_cap_exceeded_returns_fallback(self):
+        prefer, fallback = self._adapters(2)
+        policy = RoutingPolicy(rules=[
+            RoutingRule("triage", prefer=prefer, max_cost_per_1k=1.0, fallback=fallback)
+        ])
+        assert policy.resolve("triage", estimated_cost_per_1k=2.0) is fallback
+
+    def test_cost_cap_exceeded_no_fallback_returns_prefer(self):
+        """When cost exceeds cap but no fallback is set, still return prefer."""
+        prefer, *_ = self._adapters()
+        policy = RoutingPolicy(rules=[
+            RoutingRule("triage", prefer=prefer, max_cost_per_1k=0.1)
+        ])
+        assert policy.resolve("triage", estimated_cost_per_1k=5.0) is prefer
+
+    def test_no_estimated_cost_ignores_cap(self):
+        prefer, fallback = self._adapters(2)
+        policy = RoutingPolicy(rules=[
+            RoutingRule("triage", prefer=prefer, max_cost_per_1k=0.01, fallback=fallback)
+        ])
+        # No cost estimate → cap not applied
+        assert policy.resolve("triage") is prefer
+
+    def test_unknown_task_type_returns_default(self):
+        prefer, default = self._adapters(2)
+        policy = RoutingPolicy(
+            rules=[RoutingRule("triage", prefer=prefer)],
+            default=default,
+        )
+        assert policy.resolve("unknown") is default
+
+    def test_no_match_no_default_raises_lookup_error(self):
+        prefer, *_ = self._adapters()
+        policy = RoutingPolicy(rules=[RoutingRule("triage", prefer=prefer)])
+        with pytest.raises(LookupError, match="unknown"):
+            policy.resolve("unknown")
+
+    def test_empty_rules_with_default_returns_default(self):
+        default, *_ = self._adapters()
+        policy = RoutingPolicy(default=default)
+        assert policy.resolve("anything") is default
+
+    def test_empty_policy_raises(self):
+        policy = RoutingPolicy()
+        with pytest.raises(LookupError):
+            policy.resolve("triage")
+
+    def test_multiple_task_types(self):
+        a, b, c = self._adapters(3)
+        policy = RoutingPolicy(rules=[
+            RoutingRule("fast", prefer=a),
+            RoutingRule("smart", prefer=b),
+            RoutingRule("cheap", prefer=c),
+        ])
+        assert policy.resolve("fast") is a
+        assert policy.resolve("smart") is b
+        assert policy.resolve("cheap") is c