refactor(agents): prompt 外置方案A — 21 prompt 散文外迁 .md + SpecResolver

把 21 个内置 agent 的 system_prompt 从 specs.py 的 Python 常量外置为
prompts/<spec.name>.md，import 期由 load_prompt 确定性加载；建立 SPECS 名册
+ SCHEMA_CATALOG（Pydantic 类型留 Python）+ 统一只读解析入口 SpecResolver。
纯重构、零功能/schema 变更，缓存断点前块字节级不变（不变量 #9）。

@llm packages/agents（步骤1-3）
- spec_model.py：抽出 AgentSpec（frozen，字段不变）
- prompt_loader.py：load_prompt = utf-8-sig 去BOM → LF 归一 → NFC → rstrip尾LF，
  内存缓存 + fail-fast（PromptNotFoundError），import 期确定性
- schema_catalog.py：SCHEMA_CATALOG[name]→output type 唯一真相源（refiner=None）
- prompts/*.md ×21：取常量「运行时值」程序化外迁（反斜杠折行已塌缩，
  物理换行≡运行时换行）；文件名按 spec.name 连字符（style.md/character-gen.md 等）
- specs.py：删 21 常量 + AgentSpec 类；system_prompt=load_prompt(name)、
  output_schema=SCHEMA_CATALOG[name]；建 SPECS + REVIEW_RESERVED_NAMES；
  *_spec 兼容期保留且 SPECS[name] is *_spec（同一实例）。804→337 行
- __init__.py：显式 __all__ 重导出（避 F401）

@backend packages/skills（步骤4-5）
- SpecResolver：内置 SPECS（纯内存、零 DB）+ 用户 SkillRegistry 统一 get；
  内置 name 永不触发 DB；output_schema_for 精确匹配
- skill_registry：保留命名空间守卫前移至入库校验，拒同名内置 → VALIDATION
- toolbox_registry：GeneratorTool.spec 改走 SPECS[...]，删 12 个 *_spec 直接 import

@devops repo-root
- .gitattributes：prompts/*.md text eol=lf（修正：须用完整嵌套路径才匹配）
- packages/agents/pyproject：hatchling artifacts 纳入 prompts/*.md 随 wheel/sdist 分发
- ci.yml：新增 build wheel → 裸装 → import ww_agents.SPECS 冒烟

TDD 全程 mock 网关；门禁绿：ruff/format clean · mypy 209 files · pytest 744 passed
（含金标准 sha256 回归 / md↔spec↔catalog 一一对应 / fail-fast / BOM+NFC /
内置守卫 / 同一实例 / 编排器无回归 / apps/api import-smoke / 打包冒烟）

packages/skills/tests/test_spec_resolver.py

@@ -0,0 +1,149 @@
+"""SpecResolver 单测（Prompt 外置方案A · 步4）。
+
+`SpecResolver` 统一内置（`SPECS`，纯内存、零 DB）与用户 skill（`SkillRegistry`，DB）
+的只读解析入口。核心约束（不变量 #3 / 评审 HIGH）：
+
+- `get(name)` 先查内置 `SPECS`（纯内存），命中内置 name **绝不触发任何 DB/registry 调用**；
+- 未命中内置才查 `SkillRegistry`；都无 → `AppError(NOT_FOUND)`；
+- `output_schema_for`：内置 → `SCHEMA_CATALOG[name]` 真类；纯用户 skill → None；
+  name 精确字符串相等（无大小写/连字符归一），拼错近似 name → None 不报错；
+- `resolver.build` 纯合并，**不**做保留名冲突校验（守卫前移至 SkillRegistry 入库）。
+"""
+
+from __future__ import annotations
+
+import pytest
+from ww_agents import (
+    SCHEMA_CATALOG,
+    SPECS,
+    AgentSpec,
+)
+from ww_shared import AppError, ErrorCode
+from ww_skills import SpecResolver
+
+
+class _FakeRegistry:
+    """断言用 fake：记录 get/names 是否被调用（内置 get 必须零触达）。"""
+
+    def __init__(self, specs: dict[str, AgentSpec] | None = None) -> None:
+        self._specs = dict(specs or {})
+        self.get_calls: list[str] = []
+        self.names_calls: int = 0
+
+    def get(self, name: str) -> AgentSpec:
+        self.get_calls.append(name)
+        spec = self._specs.get(name)
+        if spec is None:
+            raise AppError(ErrorCode.NOT_FOUND, f"skill not found: {name}")
+        return spec
+
+    def names(self) -> list[str]:
+        self.names_calls += 1
+        return sorted(self._specs)
+
+    def list_scope(self, scope: str) -> list[AgentSpec]:
+        return [s for s in sorted(self._specs.values(), key=lambda s: s.name) if s.scope == scope]
+
+
+def _user_spec(name: str, scope: str = "custom") -> AgentSpec:
+    return AgentSpec(
+        name=name,
+        tier="writer",
+        system_prompt=f"prompt for {name}",
+        input_schema=None,
+        output_schema=None,
+        reads=(),
+        writes=(),
+        scope=scope,
+    )
+
+
+# ---- #7 resolver 内置/用户对齐 + 零 DB ----
+
+
+def test_get_builtin_returns_specs_instance_without_touching_registry() -> None:
+    # Arrange：fake registry 本身有同名条目也无所谓——内置命中必须零触达。
+    fake = _FakeRegistry({"continuity": _user_spec("continuity")})
+    resolver = SpecResolver.build(fake)
+
+    # Act
+    spec = resolver.get("continuity")
+
+    # Assert：拿到的是内置同一实例，且 registry.get 从未被调用（零 DB）。
+    assert spec is SPECS["continuity"]
+    assert fake.get_calls == []
+
+
+def test_get_user_skill_falls_through_to_registry() -> None:
+    fake = _FakeRegistry({"my-skill": _user_spec("my-skill")})
+    resolver = SpecResolver.build(fake)
+
+    spec = resolver.get("my-skill")
+
+    assert spec.name == "my-skill"
+    assert fake.get_calls == ["my-skill"]
+
+
+def test_get_unknown_everywhere_raises_not_found() -> None:
+    fake = _FakeRegistry()
+    resolver = SpecResolver.build(fake)
+
+    with pytest.raises(AppError) as exc:
+        resolver.get("nope-not-here")
+
+    assert exc.value.code is ErrorCode.NOT_FOUND
+    assert fake.get_calls == ["nope-not-here"]
+
+
+def test_names_merges_builtin_and_user() -> None:
+    fake = _FakeRegistry({"my-skill": _user_spec("my-skill")})
+    resolver = SpecResolver.build(fake)
+
+    names = resolver.names()
+
+    assert "continuity" in names
+    assert "my-skill" in names
+
+
+def test_list_scope_filters_builtin_and_user() -> None:
+    fake = _FakeRegistry({"my-skill": _user_spec("my-skill", scope="custom")})
+    resolver = SpecResolver.build(fake)
+
+    builtin = resolver.list_scope("builtin")
+    custom = resolver.list_scope("custom")
+
+    assert all(s.scope == "builtin" for s in builtin)
+    assert {s.name for s in custom} == {"my-skill"}
+
+
+# ---- #9 output_schema_for ----
+
+
+def test_output_schema_for_builtin_returns_real_type() -> None:
+    fake = _FakeRegistry()
+    resolver = SpecResolver.build(fake)
+
+    assert resolver.output_schema_for("continuity") is SCHEMA_CATALOG["continuity"]
+
+
+def test_output_schema_for_refiner_is_none() -> None:
+    fake = _FakeRegistry()
+    resolver = SpecResolver.build(fake)
+
+    assert resolver.output_schema_for("refiner") is None
+
+
+def test_output_schema_for_pure_user_skill_is_none() -> None:
+    fake = _FakeRegistry({"my-skill": _user_spec("my-skill")})
+    resolver = SpecResolver.build(fake)
+
+    assert resolver.output_schema_for("my-skill") is None
+
+
+def test_output_schema_for_misspelled_name_is_none_no_fuzzy_match() -> None:
+    # 拼错近似 name（下划线）不得误命中连字符内置 "character-gen"（精确字符串相等）。
+    fake = _FakeRegistry()
+    resolver = SpecResolver.build(fake)
+
+    assert resolver.output_schema_for("character_gen") is None
+    assert resolver.output_schema_for("character-gen") is not None