feat: 实现 Skills 支持

[BukeLy]

Summary

• 添加 hello-world 示例 Skill（演示 Skills 基本结构）
• Dockerfile: 复制 skills 到 /opt/claude-skills
• agent_session.py: 运行时复制到 /tmp/.claude-code/skills/，配置 setting_sources=['user']
• 更新 README.md 移除 Skills TODO

Test plan

• 验证 Docker 构建成功
• 验证 Skills 在运行时被正确加载
• 测试 hello-world Skill 调用

[BukeLy]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR implements Skills support for the Claude Agent SDK integration by adding a hello-world example skill, configuring Docker to bundle skills, and updating the runtime to copy skills to the appropriate location. The implementation updates documentation to reflect that Skills are now supported.

• Adds hello-world example skill demonstrating basic skill structure with reference files and scripts
• Configures Dockerfile and agent_session.py to copy skills from /opt/claude-skills to /tmp/.claude-code/skills at runtime
• Updates setting_sources configuration to enable skill loading

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/test_skills_location.py	Adds exploratory test to verify skill loading from different filesystem locations
agent-sdk-server/claude-config/skills/hello-world/SKILL.md	Defines example skill with description and usage instructions
agent-sdk-server/claude-config/skills/hello-world/scripts/print_message.py	Script that reads and outputs content from reference JSON file
agent-sdk-server/claude-config/skills/hello-world/reference/message.json	Sample JSON data referenced by the skill script
agent-sdk-server/agent_session.py	Adds runtime logic to copy skills to writable location and configures setting_sources=['user']
agent-sdk-server/Dockerfile	Copies skills directory to /opt/claude-skills for runtime access
README.md	Updates feature list and project structure to reflect Skills support

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[BukeLy]

Code review

Found 1 issue:

1. SubAgent Sources preservation guidance deleted - The system_prompt.md was rewritten and removed the "Important: Preserving SubAgent Sources" section. This guidance instructed the main agent to preserve Sources sections from SubAgent responses. The aws-support SubAgent explicitly requires returning Sources with documentation URLs (lines 24, 33 in aws-support.md), but without the preservation guidance in the system prompt, these sources may be lost when the main agent reformats responses.

https://github.com/BukeLy/OmniCloud-Ops-Agent/blob/6e6d72d001b2958407c596250caebc881401eb98/agent-sdk-server/claude-config/system_prompt.md#L1-L55

Suggestion: Add back the SubAgent Sources preservation guidance to system_prompt.md, adapted to MarkdownV2 format:

## SubAgent Sources Preservation

When using SubAgents, preserve any "Sources" section verbatim in your response\.

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