修复演示恢复默认模板覆盖逻辑

- 新增后端默认模板服务，集中维护腹腔镜胆囊切除术和头颈部CT分割的权威分类树、颜色、maskid 和层级定义。

- 演示恢复出厂设置时强制恢复系统默认模板，缺失模板会重建，已修改或删减的默认语义分类树会覆盖回默认状态。

- 清理 main.py 中重复的默认模板定义，让启动 seed 复用同一套服务逻辑，避免后续默认模板定义漂移。

- 扩展管理员恢复出厂设置测试，覆盖头颈部CT模板被改坏和腹腔镜模板缺失后的恢复结果。

- 更新 AGENTS、README 和需求/API/测试/前端审计文档，明确恢复出厂设置会权威恢复系统默认模板。

backend/main.py

@@ -24,25 +24,8 @@ logging.basicConfig(
     format="%(asctime)s | %(levelname)s | %(name)s | %(message)s",
 )
 logger = logging.getLogger(__name__)
-RESERVED_UNCLASSIFIED_CLASS = {
-    "id": "reserved-unclassified",
-    "name": "待分类",
-    "color": "#000000",
-    "zIndex": 0,
-    "maskId": 0,
-    "category": "系统保留",
-}
 
 
-def _with_reserved_unclassified_class(classes: list[dict]) -> list[dict]:
-    filtered = [
-        item for item in classes
-        if item.get("id") != RESERVED_UNCLASSIFIED_CLASS["id"]
-        and item.get("name") != RESERVED_UNCLASSIFIED_CLASS["name"]
-        and item.get("maskId") != 0
-    ]
-    return [*filtered, dict(RESERVED_UNCLASSIFIED_CLASS)]
-
 def _ensure_runtime_schema_columns() -> None:
     """Add nullable columns introduced after initial create_all deployments."""
     try:
@@ -137,8 +120,6 @@ def _seed_default_project_sync() -> None:
 
 def _seed_default_templates_sync() -> None:
     """Seed default ontology templates on first startup."""
-    from models import Template
-
     db = SessionLocal()
     try:
         ensure_default_templates(db)
@@ -148,112 +129,12 @@ def _seed_default_templates_sync() -> None:
         db.close()
 
 
-def _template_classes(
-    template_name: str,
-    names: list[str],
-    colors: list[tuple[int, int, int]],
-    *,
-    id_prefix: str,
-) -> list[dict]:
-    classes = []
-    for idx, (rgb, name) in enumerate(zip(colors, names)):
-        color_hex = f"#{rgb[0]:02x}{rgb[1]:02x}{rgb[2]:02x}"
-        classes.append({
-            "id": f"{id_prefix}-{idx}",
-            "name": name,
-            "color": color_hex,
-            "zIndex": (len(names) - idx) * 10,
-            "maskId": idx + 1,
-            "category": template_name,
-        })
-    return classes
-
-
 def ensure_default_templates(db) -> None:
     """Ensure all bundled system templates exist."""
-    from models import Template
+    from services.default_templates import ensure_default_templates as _ensure_default_templates
 
-    default_templates = [
-        {
-            "name": "腹腔镜胆囊切除术",
-            "description": "腹腔镜胆囊切除术（LC）手术器械与解剖结构语义分割模板，共35个分类",
-            "color": "#06b6d4",
-            "z_index": 0,
-            "classes": _with_reserved_unclassified_class(_template_classes(
-                "腹腔镜胆囊切除术",
-                [
-                    '针', '线', '肿瘤', '血管阻断夹', '棉球', '双极电凝',
-                    '肝脏', '胆囊', '分离钳', '脂肪', '止血海绵', '肝总管',
-                    '吸引器', '剪刀', '超声刀', '止血纱布', '胆总管', '生物夹',
-                    '无损伤钳', '钳夹', '喷洒', '胆囊管', '动脉', '电凝',
-                    '静脉', '标本袋', '引流管', '纱布', '金属钛夹', '韧带',
-                    '肝蒂', '推结器', '乳胶管-血管阻断', '吻合器', '术中超声',
-                ],
-                [
-                    (134, 124, 118), (0, 157, 142), (245, 161, 0), (255, 172, 159), (146, 175, 236), (155, 62, 0),
-                    (255, 91, 0), (255, 234, 0), (85, 111, 181), (155, 132, 0), (181, 227, 14), (72, 0, 255),
-                    (255, 0, 255), (29, 32, 136), (240, 16, 116), (160, 15, 95), (0, 155, 33), (0, 160, 233),
-                    (52, 184, 178), (66, 115, 82), (90, 120, 41), (255, 0, 0), (117, 0, 0), (167, 24, 233),
-                    (42, 8, 66), (112, 113, 150), (0, 255, 0), (255, 255, 255), (0, 255, 255), (181, 85, 105),
-                    (113, 102, 140), (202, 202, 200), (197, 83, 181), (136, 162, 196), (138, 251, 213),
-                ],
-                id_prefix="cls-lap",
-            )),
-        },
-        {
-            "name": "头颈部CT分割",
-            "description": "头颈部CT分割",
-            "color": "#ef4444",
-            "z_index": 10,
-            "classes": _with_reserved_unclassified_class(_template_classes(
-                "头颈部CT分割",
-                [
-                    "肿瘤/结节 (Tumor/Nodule)",
-                    "下颌骨 (Mandible)",
-                    "甲状腺 (Thyroid)",
-                    "气管 (Trachea)",
-                    "颈椎 (Cervical Spine)",
-                    "颈动脉 (Carotid Artery)",
-                    "颈静脉 (Jugular Vein)",
-                    "腮腺 (Parotid Gland)",
-                    "下颌下腺 (Submandibular Gland)",
-                    "舌骨 (Hyoid Bone)",
-                ],
-                [
-                    (255, 0, 0),
-                    (0, 255, 0),
-                    (0, 0, 255),
-                    (255, 255, 0),
-                    (255, 0, 255),
-                    (0, 255, 255),
-                    (255, 128, 0),
-                    (128, 0, 128),
-                    (0, 128, 128),
-                    (128, 128, 0),
-                ],
-                id_prefix="cls-head-neck-ct",
-            )),
-        },
-    ]
+    _ensure_default_templates(db)
 
-    for definition in default_templates:
-        existing = db.query(Template).filter(
-            Template.name == definition["name"],
-            Template.owner_user_id.is_(None),
-        ).first()
-        if existing is not None:
-            continue
-        template = Template(
-            name=definition["name"],
-            description=definition["description"],
-            color=definition["color"],
-            z_index=definition["z_index"],
-            mapping_rules={"classes": definition["classes"], "rules": []},
-            owner_user_id=None,
-        )
-        db.add(template)
-        logger.info("Seeded default template '%s' with %d classes", definition["name"], len(definition["classes"]))
-    db.commit()
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):