fix: remove api_key from config.yaml, read from EMBED_API_KEY env var; unify config path constant

src/server/app.py

@@ -5,7 +5,7 @@ from pathlib import Path
 from fastapi import FastAPI, HTTPException
 from pydantic import BaseModel
 
-from src.core.config import load_config, EmbedConfig
+from src.core.config import load_config, EmbedConfig, DEFAULT_CONFIG_PATH
 from src.core.db import VectorDB
 from src.core.embedder import create_embedder
 from src.core.ingest import DocumentIngestor
@@ -42,9 +42,9 @@ def _get_db():
 def _get_embedder():
     global _embedder
     if _embedder is None:
-        # 先尝试从 config.yaml 加载, 失败则用默认 local
+        # 先尝试从配置文件加载, 失败则用默认 local
         try:
-            cfg = load_config("config.yaml")
+            cfg = load_config(DEFAULT_CONFIG_PATH)
             embed_cfg = cfg.embed
         except Exception:
             embed_cfg = EmbedConfig(mode="local")
@@ -56,7 +56,7 @@ def _init_services():
     global _searcher, _ingestor
     collection = os.getenv("MD_VECTOR_DB_COLLECTION", "markdown_docs")
     try:
-        cfg = load_config("config.yaml")
+        cfg = load_config(DEFAULT_CONFIG_PATH)
         collection = cfg.chroma.collection_name
     except Exception:
         pass