bench: add benchmark runners, results docs, and test suite

Benchmarks: LongMemEval, LoCoMo, ConvoMem, MemBench runners with
methodology docs and hybrid retrieval analysis.

Tests: config, miner, convo_miner, normalize — 9 tests, all passing.

tests/test_config.py

@@ -0,0 +1,32 @@
+import os
+import json
+import tempfile
+from mempalace.config import MempalaceConfig
+
+
+def test_default_config():
+    cfg = MempalaceConfig(config_dir=tempfile.mkdtemp())
+    assert "palace" in cfg.palace_path
+    assert cfg.collection_name == "mempalace_drawers"
+
+
+def test_config_from_file():
+    tmpdir = tempfile.mkdtemp()
+    with open(os.path.join(tmpdir, "config.json"), "w") as f:
+        json.dump({"palace_path": "/custom/palace"}, f)
+    cfg = MempalaceConfig(config_dir=tmpdir)
+    assert cfg.palace_path == "/custom/palace"
+
+
+def test_env_override():
+    os.environ["MEMPALACE_PALACE_PATH"] = "/env/palace"
+    cfg = MempalaceConfig(config_dir=tempfile.mkdtemp())
+    assert cfg.palace_path == "/env/palace"
+    del os.environ["MEMPALACE_PALACE_PATH"]
+
+
+def test_init():
+    tmpdir = tempfile.mkdtemp()
+    cfg = MempalaceConfig(config_dir=tmpdir)
+    cfg.init()
+    assert os.path.exists(os.path.join(tmpdir, "config.json"))