fix: complete B-03/B-08/B-09 and add OMBRE_*_MODEL env vars

- decay_engine: keep activation_count as float (B-03);
  refresh local meta after auto_resolve so resolved_factor
  applies in the same cycle (B-08)
- server.hold(): user-supplied valence/arousal now takes
  priority over analyze() output (B-09)
- utils.load_config: support OMBRE_DEHYDRATION_MODEL
  (with OMBRE_MODEL alias) and OMBRE_EMBEDDING_MODEL
- ENV_VARS.md: document new model env vars
- tests/conftest.py: align fixture with spec-correct weights
  (time_proximity=1.5, content_weight=1.0) and feel subdir layout

utils.py

@@ -98,6 +98,16 @@ def load_config(config_path: str = None) -> dict:
     if env_buckets_dir:
         config["buckets_dir"] = env_buckets_dir
 
+    # OMBRE_DEHYDRATION_MODEL (with OMBRE_MODEL alias) overrides dehydration.model
+    env_dehy_model = os.environ.get("OMBRE_DEHYDRATION_MODEL", "") or os.environ.get("OMBRE_MODEL", "")
+    if env_dehy_model:
+        config.setdefault("dehydration", {})["model"] = env_dehy_model
+
+    # OMBRE_EMBEDDING_MODEL overrides embedding.model
+    env_embed_model = os.environ.get("OMBRE_EMBEDDING_MODEL", "")
+    if env_embed_model:
+        config.setdefault("embedding", {})["model"] = env_embed_model
+
     # --- Ensure bucket storage directories exist ---
     # --- 确保记忆桶存储目录存在 ---
     buckets_dir = config["buckets_dir"]