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

.github/skills/release-prep/SKILL.md

@@ -20,6 +20,13 @@ This skill covers:
 
 It **stops before** `git push` or `gh pr create`. Use the `pr-submitter` skill for those steps.
 
+### Temporary File Convention
+
+Any temporary files created during release prep (e.g., draft changelogs) must:
+- Be written to the project's `.temp/` directory, **NOT** system `/tmp`
+- Be cleaned up before commit using `rm -f .temp/file_name`
+- Never be committed to git (add `.temp/` to `.gitignore`)
+
 ---
 
 ## Workflow