fix: remove redundant CodingKeys conflicting with .convertFromSnakeCase

JSONDecoder.keyDecodingStrategy = .convertFromSnakeCase converts JSON keys
like 'tenant_access_token' to Swift names like 'tenantAccessToken'. Having
explicit CodingKeys that map to the ORIGINAL snake_case keys (e.g.,
case tenantAccessToken = "tenant_access_token") causes a collision:
the decoder first converts the JSON key, then looks for a CodingKey
matching the original name — but the converted name doesn't match.

Removed redundant CodingKeys from OAuthTokenData, TenantAccessTokenData,
UserInfoData, and RecordItem. .convertFromSnakeCase handles all these
mappings automatically.

Co-Authored-By: Claude <noreply@anthropic.com>

Sources/Services/Feishu/FeishuModels.swift

@@ -16,27 +16,16 @@ struct RecordListData: Decodable {
 struct RecordItem: Decodable {
     let recordId: String
     let fields: [String: JSONValue]
-
-    enum CodingKeys: String, CodingKey {
-        case recordId = "record_id"
-        case fields
-    }
 }
 
 struct OAuthTokenData: Decodable {
+    // Note: decoder uses .convertFromSnakeCase, so JSON keys are auto-mapped:
+    // access_token→accessToken, token_type→tokenType, expires_in→expiresIn, etc.
     let accessToken: String
     let tokenType: String?
     let expiresIn: Int
     let refreshToken: String?
     let refreshExpiresIn: Int?
-
-    enum CodingKeys: String, CodingKey {
-        case accessToken = "access_token"
-        case tokenType = "token_type"
-        case expiresIn = "expires_in"
-        case refreshToken = "refresh_token"
-        case refreshExpiresIn = "refresh_expires_in"
-    }
 }
 
 struct TenantAccessTokenData: Decodable {
@@ -44,23 +33,12 @@ struct TenantAccessTokenData: Decodable {
     let msg: String
     let tenantAccessToken: String
     let expire: Int
-
-    enum CodingKeys: String, CodingKey {
-        case code
-        case msg
-        case tenantAccessToken = "tenant_access_token"
-        case expire
-    }
 }
 
 struct UserInfoData: Decodable {
     let name: String?
+    // en_name → enName via .convertFromSnakeCase
     let enName: String?
-
-    enum CodingKeys: String, CodingKey {
-        case name
-        case enName = "en_name"
-    }
 }
 
 enum JSONValue: Decodable {