feat: initial commit of Claude Code configuration

Add comprehensive Claude Code setup including:
- Custom coding rules (Go, Git, Testing, Security, Patterns)
- 24 installed plugins (Voltagent, Workflows, Skills)
- Cross-platform installers (bash, PowerShell)
- Complete documentation

This configuration provides the same powerful development
environment across any Claude Code installation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

rules/coding-style.md

@@ -0,0 +1,26 @@
+# Go Coding Style
+
+> This file extends [common/coding-style.md](../common/coding-style.md) with Go specific content.
+
+## Formatting
+
+- **gofmt** and **goimports** are mandatory — no style debates
+
+## Design Principles
+
+- Accept interfaces, return structs
+- Keep interfaces small (1-3 methods)
+
+## Error Handling
+
+Always wrap errors with context:
+
+```go
+if err != nil {
+    return fmt.Errorf("failed to create user: %w", err)
+}
+```
+
+## Reference
+
+See skill: `golang-patterns` for comprehensive Go idioms and patterns.