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/TEMP_FILES_POLICY.md

@@ -0,0 +1,121 @@
+# Temporary Files Handling Policy
+
+**Last Updated**: 2026-02-26  
+**Status**: Active Guideline
+
+## Overview
+
+All temporary files created during skill execution or development workflows must follow this centralized policy to maintain project cleanliness and workspace isolation alignment.
+
+## Core Rule
+
+**Temporary files MUST be stored in the project's `.temp/` directory, NOT in system directories like `/tmp`.**
+
+## Rationale
+
+1. **Workspace Isolation**: Aligns with OpenWebUI's workspace-per-user model
+2. **Project Cohesion**: All project artifacts (temporary or permanent) stay within project boundaries
+3. **Multi-User Safety**: Avoids conflicts between multiple developers using the same system
+4. **Cleanup Traceability**: Easy to verify all temp files are cleaned up via single `.temp/` directory
+5. **Debugging**: Inspectable before deletion if issues occur
+
+## Usage Pattern
+
+### Creating Temp File
+
+```bash
+# Step 1: Ensure temp directory exists
+mkdir -p .temp
+
+# Step 2: Write temp file
+cat > .temp/my_temp_file.md << 'EOF'
+...content...
+EOF
+
+# Step 3: Use the file in your workflow
+# (e.g., pass to gh CLI, process with script, etc.)
+```
+
+### Cleanup After Use
+
+```bash
+# Remove individual temp files
+rm -f .temp/my_temp_file.md
+
+# Or full cleanup of entire temp directory
+rm -rf .temp/
+```
+
+## Skills Affected
+
+| Skill | Implementation | Status |
+|-------|----------------|--------|
+| `pr-submitter` | PR body file (`.temp/pr_body.md`) | ✅ Updated |
+| `release-prep` | Draft notes (if any) | ✅ Policy Added |
+| `version-bumper` | Backup files (if any) | ℹ️ Check needed |
+| Future skills | TBD | 📋 Must follow policy |
+
+## .gitignore Configuration
+
+The following entry in `.gitignore` ensures temp files are never committed:
+
+```
+# Temporary files
+.temp/
+.build/
+```
+
+## Examples
+
+### Example 1: PR Submitter Skill
+```bash
+# Create PR body in temp directory
+mkdir -p .temp
+cat > .temp/pr_body.md << 'EOF'
+## Summary
+New feature implementation
+EOF
+
+# Use with gh CLI
+gh pr create --body-file .temp/pr_body.md --title "feat: new feature"
+
+# Cleanup
+rm -f .temp/pr_body.md
+```
+
+### Example 2: Release Prepare Workflow
+```bash
+# Create draft changelog
+mkdir -p .temp
+cat > .temp/changelog_draft.md << 'EOF'
+# v1.0.0 Release Notes
+EOF
+
+# Edit, validate, then integrate into real files
+# ...
+
+# Cleanup
+rm -f .temp/changelog_draft.md
+```
+
+## Anti-Patterns (❌ Don't Do This)
+
+- ❌ Writing temp files to `/tmp` — will be lost/orphaned
+- ❌ Writing to root directory or `plugins/` — pollutes repo
+- ❌ Not cleaning up temp files — accumulates clutter
+- ❌ Committing `.temp/` files to git — defeats the purpose
+- ❌ Using absolute paths — breaks workflow portability
+
+## Enforcement
+
+1. **Code Review**: PRs should verify no `/tmp` references in scripts
+2. **CI/CD**: Setup can validate `.temp/` cleanup via git status before commit
+3. **Documentation**: All skill docs must reference this policy (link to this file)
+4. **Automated**: Consider adding pre-commit hook to ensure `.temp/` is not staged
+
+## Questions / Clarifications
+
+For questions about this policy, refer to:
+- `.github/skills/pr-submitter/SKILL.md` — Practical example
+- `.github/skills/release-prep/SKILL.md` — Policy integration
+- `/memories/repo/temp-file-handling-convention.md` — Internal notes