feat(provider): 增加 Claude Code 适配器、高级配置能力与 OAuth 账号类型统一解析

- 新增 Claude Code provider adapter (context, envelope, plugin, constants)
- 扩展 provider admin 路由，支持 Claude Code 高级配置 (CRUD)
- 统一 OAuth 账号类型解析逻辑，前后端对齐
- 重构 BatchAssignModelsDialog / ModelMappingDialog，简化组件逻辑
- handler 基类增强: request_builder 支持 Claude Code 信封格式
- CLI stream/sync mixin 适配 Claude Code 流式与同步模式
- 扩展 candidate builder / failover / scheduler 对 Claude Code 的支持
- 前端增加请求时间线可视化 (HorizontalRequestTimeline)
- 补充 Claude Code envelope / runtime controls / distributed sessions 等测试

Closes #183
Closes #185

Co-Authored-By: AAEE86 <ppk0227@hotmail.com>

tests/services/test_admin_provider_defaults.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+import pytest
+
+from src.api.admin.providers.routes import (
+    _merge_claude_code_advanced_config,
+    _should_enable_format_conversion_by_default,
+)
+from src.core.exceptions import InvalidRequestException
+
+
+def test_claude_code_defaults_format_conversion_enabled() -> None:
+    assert _should_enable_format_conversion_by_default("claude_code") is True
+
+
+def test_custom_defaults_format_conversion_disabled() -> None:
+    assert _should_enable_format_conversion_by_default("custom") is False
+
+
+def test_merge_claude_code_advanced_clears_stale_config_for_non_claude_provider() -> None:
+    merged, changed = _merge_claude_code_advanced_config(
+        provider_type="custom",
+        provider_config={"foo": "bar", "claude_code_advanced": {"max_sessions": 9}},
+        claude_code_advanced=None,
+        claude_advanced_in_payload=False,
+    )
+
+    assert merged == {"foo": "bar"}
+    assert changed is True
+
+
+def test_merge_claude_code_advanced_rejects_non_claude_payload() -> None:
+    with pytest.raises(InvalidRequestException):
+        _merge_claude_code_advanced_config(
+            provider_type="custom",
+            provider_config={},
+            claude_code_advanced={"max_sessions": 9},
+            claude_advanced_in_payload=True,
+        )