feat: Migrate pipeline debug from SSE to WebSocket

[RockChinQ]

Replace Server-Sent Events (SSE) with WebSocket for pipeline debugging to support bidirectional real-time communication and resolve timeout limitations.

Backend Changes

• Add WebSocketConnectionPool for managing client connections
• Implement WebSocket route handler at /api/v1/pipelines//chat/ws
• Modify WebChatAdapter to broadcast messages via WebSocket
• Support both legacy SSE and new WebSocket simultaneously
• Maintain person/group session isolation

Frontend Changes

• Create PipelineWebSocketClient for WebSocket communication
• Update DebugDialog to use WebSocket instead of SSE
• Support auto-reconnection and connection status tracking
• Remove streaming toggle (WebSocket always supports streaming)

Key Features

• Eliminates 120-second timeout limitation
• Supports multiple messages per request
• Enables backend push notifications (plugins)
• Maintains session isolation (person vs group)
• Backward compatible with SSE during transition

🤖 Generated with Claude Code

概述 / Overview

请在此部分填写你实现/解决/优化的内容:
Summary of what you implemented/solved/optimized:

检查清单 / Checklist

PR 作者完成 / For PR author

请在方括号间写x以打勾 / Please tick the box with x

• 阅读仓库贡献指引了吗？ / Have you read the contribution guide?
• 与项目所有者沟通过了吗？ / Have you communicated with the project maintainer?
• 我确定已自行测试所作的更改，确保功能符合预期。 / I have tested the changes and ensured they work as expected.

项目维护者完成 / For project maintainer

• 相关 issues 链接了吗？ / Have you linked the related issues?
• 配置项写好了吗？迁移写好了吗？生效了吗？ / Have you written the configuration items? Have you written the migration? Has it taken effect?
• 依赖加到 pyproject.toml 和 core/bootutils/deps.py 了吗 / Have you added the dependencies to pyproject.toml and core/bootutils/deps.py?
• 文档编写了吗？ / Have you written the documentation?

[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 172 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../api/http/controller/groups/pipelines/websocket.py	11.00%	97 Missing ⚠️
pkg/api/http/service/websocket_pool.py	36.14%	53 Missing ⚠️
pkg/platform/sources/webchat.py	0.00%	17 Missing ⚠️
pkg/core/stages/build_app.py	0.00%	5 Missing ⚠️

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