feat: add base_url env vars, iCloud conflict detector, user compose guidance

- utils.py: support OMBRE_DEHYDRATION_BASE_URL and OMBRE_EMBEDDING_BASE_URL
  so Gemini/non-DeepSeek users can configure without mounting a custom config
- docker-compose.user.yml: pass all 4 model/url env vars from .env;
  add commented Gemini example + optional config.yaml mount hint
- ENV_VARS.md: document OMBRE_DEHYDRATION_BASE_URL and OMBRE_EMBEDDING_BASE_URL
- check_icloud_conflicts.py: scan bucket dir for iCloud conflict artefacts
  and duplicate bucket IDs (report-only, no file modifications)

utils.py

@@ -103,11 +103,21 @@ def load_config(config_path: str = None) -> dict:
     if env_dehy_model:
         config.setdefault("dehydration", {})["model"] = env_dehy_model
 
+    # OMBRE_DEHYDRATION_BASE_URL overrides dehydration.base_url
+    env_dehy_base_url = os.environ.get("OMBRE_DEHYDRATION_BASE_URL", "")
+    if env_dehy_base_url:
+        config.setdefault("dehydration", {})["base_url"] = env_dehy_base_url
+
     # 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
 
+    # OMBRE_EMBEDDING_BASE_URL overrides embedding.base_url
+    env_embed_base_url = os.environ.get("OMBRE_EMBEDDING_BASE_URL", "")
+    if env_embed_base_url:
+        config.setdefault("embedding", {})["base_url"] = env_embed_base_url
+
     # --- Ensure bucket storage directories exist ---
     # --- 确保记忆桶存储目录存在 ---
     buckets_dir = config["buckets_dir"]