docs(claude): add CLAUDE.md with development rules (#2)

Author: CalvinAllen

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Critical Rules
+
+**These rules override all other instructions:**
+
+1. **NEVER commit directly to main** - Always create a feature branch and submit a pull request
+2. **Conventional commits** - Format: `type(scope): description`
+3. **GitHub Issues for TODOs** - Use `gh` CLI to manage issues, no local TODO files. Use conventional commit format for issue titles
+4. **Pull Request titles** - Use conventional commit format (same as commits)
+5. **Branch naming** - Use format: `type/scope/short-description` (e.g., `feat/ui/settings-dialog`)
+6. **Working an issue** - Always create a new branch from an updated main branch
+7. **Check branch status before pushing** - Verify the remote tracking branch still exists. If a PR was merged/deleted, create a new branch from main instead
+8. **WPF for all UI** - All UI must be implemented using WPF (XAML/C#). No web-based technologies (HTML, JavaScript, WebView)
+
+### VSIX Development Rules
+
+**Solution & Project Structure:**
+- SLNX solution files only (no legacy .sln)
+- Solution naming: `CodingWithCalvin.<ProjectFolder>`
+- Primary project naming: `CodingWithCalvin.<ProjectFolder>`
+- Additional project naming: `CodingWithCalvin.<ProjectFolder>.<Classifier>`
+
+**Build Configuration:**
+- Configurations: Debug and Release
+- Platform: AnyCPU
+- Build Tools: Latest 17.* release
+- VSSDK: Latest 17.* release
+
+**Target Frameworks:**
+- Main VSIX project: .NET Framework 4.8
+- Library projects: .NET Standard 2.0 (may use SDK-style project format)
+
+**VSIX Manifest:**
+- Version range: `[17.0,19.0)` — supports VS 2022 through VS 2026
+- Architectures: AMD64 and ARM64
+- Prerequisites: List Community edition only (captures Pro/Enterprise)
+
+**CI/CD:**
+- Build workflow: Automated build on push/PR
+- Publish workflow: Automated marketplace publishing
+- Marketplace config: `publish.manifest.json` for automated publishing
+
+**Development Environment:**
+- Required extension: Extensibility Essentials 2022
+- Helper library: VsixCommunity Toolkit
+
+**Documentation:**
+- README should be exciting and use emojis
+
+---
+
+### GitHub CLI Commands
+
+```bash
+gh issue list                    # List open issues
+gh issue view <number>           # View details
+gh issue create --title "type(scope): description" --body "..."
+gh issue close <number>
+```
+
+### Conventional Commit Types
+
+| Type | Description |
+|------|-------------|
+| `feat` | New feature |
+| `fix` | Bug fix |
+| `docs` | Documentation only |
+| `refactor` | Code change that neither fixes a bug nor adds a feature |
+| `test` | Adding or updating tests |
+| `chore` | Maintenance tasks |