feat(templates): F3b 模板库 repo + 端点（GET/POST/DELETE /templates）

- TemplateRepo/SqlTemplateRepo（list/create/delete，owner stub 过滤，只 flush 端点 commit）
- schemas/templates.py（title/body min_length=1→422）+ routers/templates.py（删不存在→404）+ main 注册
- 单测：repo CRUD/owner 隔离/frozen + 端点 201/列出/204/422×2/404

apps/api/ww_api/services/project_deps.py

@@ -29,6 +29,7 @@ from ww_core.domain.repositories import MemoryRepos, OutlineRepo, RulesRepo
 from ww_core.domain.review_repo import ReviewRepo, SqlReviewRepo
 from ww_core.domain.rule_repo import RuleWriteRepo, SqlRuleWriteRepo
 from ww_core.domain.style_repo import SqlStyleFingerprintWriteRepo, StyleFingerprintWriteRepo
+from ww_core.domain.template_repo import SqlTemplateRepo, TemplateRepo
 from ww_core.domain.world_entity_repo import SqlWorldEntityWriteRepo, WorldEntityWriteRepo
 from ww_core.memory.sql_repositories import SqlOutlineRepo, SqlRulesRepo, sql_memory_repos
 from ww_db import get_session, get_sessionmaker
@@ -159,6 +160,16 @@ def get_rule_write_repo(
     return SqlRuleWriteRepo(session)
 
 
+async def get_template_repo(
+    session: Annotated[AsyncSession, Depends(get_session)],
+) -> TemplateRepo:
+    """模板库 repo（GET/POST/DELETE /templates；create/delete 只 flush，端点提交）。
+
+    测试经 `app.dependency_overrides` 注入内存 fake。
+    """
+    return SqlTemplateRepo(session)
+
+
 async def get_skill_registry(
     session: Annotated[AsyncSession, Depends(get_session)],
 ) -> SkillRegistry: