feat(auth)!: migrate customer metadata auth

Remove local auth and user-management endpoints in favor of Keycloak-backed metadata users, project context, admin metadata APIs, and agent auth context.

app/core/encryption.py

@@ -20,10 +20,10 @@ class Encryptor:
             key: 加密密钥，如果为 None 则从环境变量读取
         """
         if key is None:
-            key_str = os.getenv("ENCRYPTION_KEY") or settings.ENCRYPTION_KEY
+            key_str = os.getenv("DATABASE_ENCRYPTION_KEY") or settings.DATABASE_ENCRYPTION_KEY
             if not key_str:
                 raise ValueError(
-                    "ENCRYPTION_KEY not found in environment variables or .env. "
+                    "DATABASE_ENCRYPTION_KEY not found in environment variables or .env. "
                     "Generate one using: Encryptor.generate_key()"
                 )
             key = key_str.encode()
@@ -80,15 +80,13 @@ _database_encryptor: Optional[Encryptor] = None
 
 
 def is_encryption_configured() -> bool:
-    return bool(os.getenv("ENCRYPTION_KEY") or settings.ENCRYPTION_KEY)
+    return is_database_encryption_configured()
 
 
 def is_database_encryption_configured() -> bool:
     return bool(
         os.getenv("DATABASE_ENCRYPTION_KEY")
         or settings.DATABASE_ENCRYPTION_KEY
-        or os.getenv("ENCRYPTION_KEY")
-        or settings.ENCRYPTION_KEY
     )
 
 
@@ -107,8 +105,6 @@ def get_database_encryptor() -> Encryptor:
         key_str = (
             os.getenv("DATABASE_ENCRYPTION_KEY")
             or settings.DATABASE_ENCRYPTION_KEY
-            or os.getenv("ENCRYPTION_KEY")
-            or settings.ENCRYPTION_KEY
         )
         if not key_str:
             raise ValueError(