test: expand coverage from 20 to 92 tests, migrate to uv

- Migrate from setuptools to hatchling build backend
- Add dependency-groups (PEP 735) for dev tooling (pytest, ruff)
- Remove redundant requirements.txt in favor of uv.lock
- Fix __version__ mismatch (2.0.0 -> 3.0.0 to match pyproject.toml)

New test files:
- conftest.py: shared fixtures (isolated palace, KG, ChromaDB collection)
- test_knowledge_graph.py: 17 tests (entity CRUD, temporal queries, timeline)
- test_mcp_server.py: 25 tests (protocol dispatch, read/write/KG/diary tools)
- test_searcher.py: 7 tests (search_memories API, filters, error handling)
- test_dialect.py: 13 tests (AAAK compression, entity/emotion detection, zettel encoding)

All 92 tests pass on Python 3.13 with chromadb 0.6.3.

tests/test_searcher.py

@@ -0,0 +1,50 @@
+"""
+test_searcher.py — Tests for the programmatic search_memories API.
+
+Tests the library-facing search interface (not the CLI print variant).
+"""
+
+import chromadb
+
+from mempalace.searcher import search_memories
+
+
+class TestSearchMemories:
+    def test_basic_search(self, palace_path, seeded_collection):
+        result = search_memories("JWT authentication", palace_path)
+        assert "results" in result
+        assert len(result["results"]) > 0
+        assert result["query"] == "JWT authentication"
+
+    def test_wing_filter(self, palace_path, seeded_collection):
+        result = search_memories("planning", palace_path, wing="notes")
+        assert all(r["wing"] == "notes" for r in result["results"])
+
+    def test_room_filter(self, palace_path, seeded_collection):
+        result = search_memories("database", palace_path, room="backend")
+        assert all(r["room"] == "backend" for r in result["results"])
+
+    def test_wing_and_room_filter(self, palace_path, seeded_collection):
+        result = search_memories("code", palace_path, wing="project", room="frontend")
+        assert all(
+            r["wing"] == "project" and r["room"] == "frontend"
+            for r in result["results"]
+        )
+
+    def test_n_results_limit(self, palace_path, seeded_collection):
+        result = search_memories("code", palace_path, n_results=2)
+        assert len(result["results"]) <= 2
+
+    def test_no_palace_returns_error(self):
+        result = search_memories("anything", "/nonexistent/path")
+        assert "error" in result
+
+    def test_result_fields(self, palace_path, seeded_collection):
+        result = search_memories("authentication", palace_path)
+        hit = result["results"][0]
+        assert "text" in hit
+        assert "wing" in hit
+        assert "room" in hit
+        assert "source_file" in hit
+        assert "similarity" in hit
+        assert isinstance(hit["similarity"], float)