feat(github-copilot-sdk): add workspace skills support (v0.9.0) (#51)

* feat(github-copilot-sdk): add workspace skills support

- Introduce ENABLE_WORKSPACE_SKILLS valve to enable/disable workspace custom tools discovery
- Modify _build_session_config() to auto-load tools from .copilot-skills/ directory
- Add workspace_skills_example.py template with 3 working example tools
- Update README.md and README_CN.md with Workspace Skills guide and usage examples
- Create v0.9.0.md and v0.9.0_CN.md release notes
- Sync version to all docs files (index.md, index.zh.md, and main docs)
- Bump version from 0.8.0 to 0.9.0 across all 7+ locations

* docs: establish temp files handling policy (project-based, not /tmp)

- Add TEMP_FILES_POLICY.md guideline for all skills and workflows
- Update pr-submitter skill to use .temp/ directory instead of /tmp
- Update release-prep skill documentation with temp file convention
- Add .temp/ and .build/ entries to .gitignore
- Create internal policy memo in /memories/repo/

This policy ensures:
- All temporary files stay within project workspace (not system /tmp)
- Alignment with OpenWebUI workspace isolation principles
- Multi-user safety and cleanup traceability
- Consistent handling across all skills and development workflows

* fix(terminology): rename 'workspace skills' to 'workspace custom tools' for accuracy

The term 'Skills' in Anthropic context refers to instruction-based frameworks
(SKILL.md files with YAML frontmatter + markdown), not custom tool functions.

Our implementation uses @define_tool decorator to define custom tools that the
SDK auto-discovers from .copilot-skills/ directory. These are Tools, not Skills.

Changes:
- Rename ENABLE_WORKSPACE_SKILLS valve -> ENABLE_WORKSPACE_TOOLS
- Update all documentation (README, README_CN, docs, release notes)
- Fix section headings and descriptions throughout
- Ensure consistent terminology across all files

This is a terminology-only change; functionality remains identical.

* feat(pipes): release v0.9.0 of GitHub Copilot SDK Pipe

- Integrated OpenWebUI Skills Bridge and manage_skills tool
- Reinforced status bar stability with session_finalized logic
- Added persistent SDK config directory support

* docs(pipes): add comprehensive guides and v0.9.0 notes for Copilot SDK

- Added skill manager and best practices guides
- Added publishing tool documentation
- Included v0.9.0 release notes and deployment script
- Updated usage guides

docs/plugins/pipes/index.zh.md

@@ -15,7 +15,7 @@ Pipes 可以用于：
 
 ## 可用的 Pipe 插件
 
-- [GitHub Copilot SDK](github-copilot-sdk.zh.md) (v0.8.0) - GitHub Copilot SDK 官方集成。具备**工作区安全隔离**、**数据库持久化**、**零配置工具桥接**与**BYOK (自带 Key) 支持**。支持流式输出、打字机思考过程及无限会话。[查看深度架构解析](github-copilot-sdk-deep-dive.zh.md) | [**查看进阶实战教程**](github-copilot-sdk-tutorial.zh.md)。
+- [GitHub Copilot SDK](github-copilot-sdk.zh.md) (v0.9.0) - GitHub Copilot SDK 官方集成。具备**工作区安全隔离**、**零配置工具桥接**与**BYOK (自带 Key) 支持**。**v0.9.0 重量级更新：OpenWebUI Skills 桥接**、状态栏稳定性加固，以及持久化 SDK 配置目录管理（`COPILOTSDK_CONFIG_DIR`）。[查看深度架构解析](github-copilot-sdk-deep-dive.zh.md) | [**查看进阶实战教程**](github-copilot-sdk-tutorial.zh.md) | [**查看详细使用手册**](github-copilot-sdk-usage-guide.zh.md)。
 - **[实战案例：GitHub 100 Star 增长预测](star-prediction-example.zh.md)** - 展示如何使用 GitHub Copilot SDK Pipe 结合 Minimax 2.1 模型，自动编写脚本分析 CSV 数据并生成详细的项目增长报告。
 - **[实战案例：视频高质量 GIF 转换与加速](video-processing-example.zh.md)** - 演示模型如何通过底层 FFmpeg 工具对录屏进行加速、缩放及双阶段色彩优化处理。