feat: M4 文风 + M5 生成/多provider/Skill + Kimi Code 订阅接入 + 本地联调修复

M4（文风）: style-auditor 双轨（提取指纹/漂移第四审）+ jobs 长任务框架(zombie reaper) + 回炉 refine + GET /style read-back。
M5（生成+扩展）: worldbuilder/character-gen（入库 continuity 409 gate + partition_writes 白名单 + schema→JSONB 形变）；
  网关多 provider 回退链/熔断/能力降级（Anthropic/Gemini 适配器）；Skill registry + 表权限沙箱 + 规则；
  前端 角色生成器/世界观/Codex/规则页/技能库/⌘K 命令面板。
K1（Kimi Code 订阅接入）: OAuth device-flow（kimi-code）+ 静态 Console key（kimi-code-key）两路径；
  coding 端点 KimiCLI 伪造头（实测 UA allow-list 门禁，缺则 403）+ JSON 模式结构化（thinking ⊥ tool_choice）。
本地联调修复: CORS 中间件；assemble 注入 premise+「写第N章」指令（修空 prompt 400）；
  GET /outline·/draft read-back + 大纲/工作台/审稿页重载；写页 client/server 常量边界 + notFound 健壮化；
  字数 toLocaleString locale 水合；审稿页终稿从已存草稿 seed（修 accept 422）。
门禁: backend ruff/mypy(157)/alembic 无漂移/pytest 451 · frontend lint/tsc/vitest/build。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/api/tests/test_gateway_fallback_wiring.py

@@ -0,0 +1,100 @@
+"""T5.2/T5.4 接线：`build_gateway_for_tier` 据 DB tier_routing 装配多 provider 回退链。
+
+不联网：只断言网关被装配了**多个适配器** + 注入了回退链解析器（chain_resolver），
+故链长 > 1。真实回退/降级行为由 packages/llm_gateway 单测 + T5.7 E2E 覆盖。
+"""
+
+from __future__ import annotations
+
+import os
+
+import pytest
+from fakes_projects import FakeSession
+from fakes_providers import FakeCredentialStore
+from ww_api.services.credentials import STUB_OWNER_ID, StoredRouting
+
+# 真 Fernet key（测试加解密凭据用；仅本测试，非生产密钥）。
+_ENC_KEY = "imB6TEcV2AzlpXjR4NjTgK_9Zt-OoqaLFQc3XqBQ0CQ="
+
+
+def _store_with_creds(*providers: str) -> FakeCredentialStore:
+    from ww_api.security.credentials import encrypt_api_key
+
+    store = FakeCredentialStore()
+    for p in providers:
+        store.creds[(STUB_OWNER_ID, p)] = encrypt_api_key("sk-test", key=_ENC_KEY)
+    return store
+
+
+@pytest.mark.asyncio
+async def test_build_gateway_wires_fallback_chain_with_multiple_adapters() -> None:
+    os.environ["CREDENTIAL_ENC_KEY"] = _ENC_KEY
+    from ww_config import get_settings
+
+    get_settings.cache_clear()
+    from ww_api.services.project_deps import build_gateway_for_tier
+
+    store = _store_with_creds("deepseek", "kimi")
+    store.routing["writer"] = StoredRouting(
+        tier="writer", provider="deepseek", model="deepseek-chat", fallback=["kimi:moonshot-v1-8k"]
+    )
+
+    gateway = await build_gateway_for_tier(FakeSession(), store, "writer")
+
+    # 两个 provider 的适配器都装配进网关 → 回退链可绕过首个失败者。
+    assert set(gateway._adapters) == {"deepseek", "kimi"}  # noqa: SLF001
+    # chain_resolver 注入 → 链长 2（去重保序）。
+    chain = gateway._resolve_chain("writer")  # noqa: SLF001
+    assert [r.provider for r in chain] == ["deepseek", "kimi"]
+
+
+@pytest.mark.asyncio
+async def test_build_gateway_single_provider_still_works() -> None:
+    """无 fallback 的路由行：单元素链（M1 行为不变，向后兼容）。"""
+    os.environ["CREDENTIAL_ENC_KEY"] = _ENC_KEY
+    from ww_config import get_settings
+
+    get_settings.cache_clear()
+    from ww_api.services.project_deps import build_gateway_for_tier
+
+    store = _store_with_creds("deepseek")
+    store.routing["analyst"] = StoredRouting(
+        tier="analyst", provider="deepseek", model="deepseek-chat", fallback=[]
+    )
+
+    gateway = await build_gateway_for_tier(FakeSession(), store, "analyst")
+    assert set(gateway._adapters) == {"deepseek"}  # noqa: SLF001
+    chain = gateway._resolve_chain("analyst")  # noqa: SLF001
+    assert len(chain) == 1
+
+
+@pytest.mark.asyncio
+async def test_build_gateway_no_routing_row_falls_back_to_global_default() -> None:
+    """无 DB 路由行 → 退回全局 resolve_route（单 provider）。"""
+    os.environ["CREDENTIAL_ENC_KEY"] = _ENC_KEY
+    from ww_config import get_settings
+
+    get_settings.cache_clear()
+    from ww_api.services.project_deps import build_gateway_for_tier
+
+    store = _store_with_creds("deepseek")  # 无 routing 行
+    gateway = await build_gateway_for_tier(FakeSession(), store, "writer")
+    assert "deepseek" in gateway._adapters  # noqa: SLF001
+
+
+@pytest.mark.asyncio
+async def test_build_gateway_no_usable_credentials_raises_503() -> None:
+    os.environ["CREDENTIAL_ENC_KEY"] = _ENC_KEY
+    from ww_config import get_settings
+
+    get_settings.cache_clear()
+    from ww_api.services.project_deps import build_gateway_for_tier
+    from ww_shared import AppError, ErrorCode
+
+    store = FakeCredentialStore()  # 无任何凭据
+    store.routing["writer"] = StoredRouting(
+        tier="writer", provider="deepseek", model="deepseek-chat", fallback=["kimi:moonshot-v1-8k"]
+    )
+    with pytest.raises(AppError) as exc:
+        await build_gateway_for_tier(FakeSession(), store, "writer")
+    assert exc.value.code == ErrorCode.LLM_UNAVAILABLE