sync: improve capabilities, streaming, and task reliability

[Luhaozhu]

Summary / 概述

This maintainer sync regenerates the Community Edition mirror from the latest upstream source.

• Tighten scheduled-task validation, run accounting, cancellation behavior, project editing, site continuity, citation highlighting, and integration status handling.
• Standardize capability-center terminology around Skills, Agents, Connectors, and Plugins, including a safe backfill for untouched legacy navigation defaults.
• Repair MCP marketplace revalidation so reviewed remote schema changes can be accepted as immutable versions and remain installable when the original source record is unavailable.
• Keep attachment parsing off the event loop and preserve streaming when a provider emits no reasoning tokens by declaring structured-reasoning behavior per model.
• Add rich table copying with HTML and plain-text clipboard formats so tables paste into Word, WPS, and email clients as real bordered tables.
• Add CE translation coverage and regression tests for marketplace revalidation, legacy page configuration, non-blocking file parsing, and structured reasoning.

Compared with the current public main, this branch updates 125 files with 2,664 insertions and 452 deletions across the generated backend, frontend, Docker, tests, and bilingual documentation.

Related issue / 关联 Issue

No single issue. This is a scheduled maintainer sync containing the latest upstream fixes.

Type of change / 变更类型

• 📖 Documentation (document/**, README*.md)
• 🧩 Example / sample (examples/**)
• 🔧 Repo meta (CI, templates, .github/**)
• Other (please describe / 请说明): Maintainer-generated Community Edition synchronization

Checklist / 检查项

• My change only touches non-generated paths (docs / examples / repo meta). 仅改动非生成路径。
• Links and code snippets were verified. 链接与代码片段已验证。
• For bilingual docs, I updated both document/en/** and document/zh-CN/** where applicable. 双语文档已同步更新（如适用）。
• I read CONTRIBUTING.md. 我已阅读贡献指南。

Validation

• python scripts/build_ce.py --import-check --pytest-check --frontend-check
• CE required-file, forbidden-artifact, binary-allowlist, brand, split, and license gates
• Backend import, OpenAPI, ORM, and CE release regression checks
• Frontend i18n, TypeScript, Vite production build, and precompression checks
• git diff --check