[ISSUE #15416] Support Nacos-managed skill subscriptions

[saynoword]

Please do not create a Pull Request without creating an issue first.

What is the purpose of the change

Add Nacos-managed skill subscriptions so users can maintain per-user, per-namespace skill subscription lists from Nacos and let CLI registry mode read the current user's subscription list. This stores subscriptions in Config without adding a new table, exposes admin/console management APIs plus a client read API, and wires the old console and next console subscription workflows. Closes #15416.

Brief changelog

• Add skill subscription API models, Config-backed storage, admin subscription service, and current-user client subscription read service.
• Add admin APIs for listing, subscribing, and unsubscribing skills, plus a client API that only reads the current request user's subscriptions.
• Wire console maintainer/inner/noop handlers and old console skill management subscription UI.
• Add next console subscription state, single and batch subscription actions, "My subscriptions" filtering, skill detail subscription controls, and synced static assets.
• Update skill specs, API surface docs, OpenAPI scenario coverage, and targeted unit/API tests.

Verifying this change

• mvn -pl api,ai,maintainer-client,test/openapi-test -DskipTests spotless:apply
• mvn -pl api,ai,maintainer-client,test/openapi-test -DskipTests spotless:check
• mvn -pl ai -am -Dtest=SkillAdminControllerTest,SkillSubscriptionServiceImplTest,ConfigSkillSubscriptionStorageTest -Dsurefire.failIfNoSpecifiedTests=false test
• mvn -pl console -am -Dtest=ConsoleSkillControllerTest,SkillProxyTest,SkillInnerHandlerTest,SkillRemoteHandlerTest -Dsurefire.failIfNoSpecifiedTests=false test
• mvn -pl ai -am -Dtest=SkillClientControllerTest,ConfigSkillSubscriptionStorageTest,SkillSubscriptionServiceImplTest,SkillClientSubscriptionServiceImplTest -Dsurefire.failIfNoSpecifiedTests=false test
• mvn -pl test/openapi-test -DskipTests test-compile
• npx eslint src/pages/skillManagement/index.tsx

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[github-actions]

Thanks for your this PR. 🙏
Please check again for your PR changes whether contains any usage/api/configuration change such as Add new API , Add new configuration, Change default value of configuration.
If so, please add or update documents(markdown type) in docs/next/ for repository nacos-group/nacos-group.github.io

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感谢您提交的PR。 🙏
请再次查看您的PR内容，确认是否包含任何使用方式/API/配置参数的变更，如：新增API、新增配置参数、修改默认配置等操作。
如果是，请确保在提交之前，在仓库nacos-group/nacos-group.github.io中的docs/next/目录下添加或更新文档（markdown格式）。

[nacos-community]

⚠️ Merge conflict detected

This PR has conflicts with the develop branch and cannot be merged in its current state. Please rebase or merge develop into your branch and resolve the conflicts:

git fetch origin
git checkout feat/subscribe-skill
git rebase origin/develop
# resolve conflicts, then:
git push --force-with-lease

This is a one-time reminder. Feel free to @mention me for a re-review after conflicts are resolved.

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