feat(roundtable): 会商席位「技能识别强化」改为按需开关(智能体级 + 链条每席位级)

弱模型补偿指令从全域生效改为默认关闭、两个 opt-in 开关取 OR:
- 智能体级: AgentConfig.seat_skill_directive(config.yaml),在智能体编辑弹窗
  (agent-card / agent-detail-panel)开关;agents 路由 create/update/读写全程穿。
- 业务链条每席位级: 存进链条 seats JSON(ChainSeatSchema.seat_skill_directive,
  无需 DB 列/迁移),在链条编辑器每个席位卡片右侧 ✨ 图标→下拉框(开关+说明)配置;
  按 agentId 查表穿到前台 useStep2Orchestration 各席位调用 + 后台作业
  seat_skill_directives:{agentId:bool} → InProcessRoundtableGateway.run_seat。
- ROUNDTABLE_SEAT_SKILL_DIRECTIVE 降级为总熔断开关(默认放行,不再 force-on)。

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

frontend-web/src/pages/NewAgentPage.tsx

@@ -83,6 +83,8 @@ export default function NewAgentPage() {
   const [modelInput, setModelInput] = useState<string>("");
   const [chatModelInput, setChatModelInput] = useState<string>("");
   const [templateNameInput, setTemplateNameInput] = useState("");
+  // 会商席位「技能识别强化」开关（弱模型补偿）。默认关。
+  const [seatSkillDirectiveInput, setSeatSkillDirectiveInput] = useState(false);
   const [formError, setFormError] = useState("");
   const [agentId, setAgentId] = useState("");
   const [agent, setAgent] = useState<Agent | null>(null);
@@ -230,6 +232,7 @@ export default function NewAgentPage() {
           skills: selectedSkills,
           model: modelOverride,
           template_name: templateNameInput.trim(),
+          seat_skill_directive: seatSkillDirectiveInput,
         });
         setAgent(updated);
         return updated;
@@ -251,6 +254,7 @@ export default function NewAgentPage() {
         skills: selectedSkills,
         model: modelOverride,
         template_name: templateNameInput.trim(),
+        seat_skill_directive: seatSkillDirectiveInput,
       });
       setAgentId(created.id);
       setAgent(created);
@@ -281,6 +285,7 @@ export default function NewAgentPage() {
     selectedSkills,
     soulInput,
     templateNameInput,
+    seatSkillDirectiveInput,
     t.agents.nameStepCheckError,
     t.agents.nameStepNetworkError,
     validateForm,