chore: initial backup of Claude Code configuration

Includes: CLAUDE.md, settings.json, agents, commands, rules, skills,
hooks, contexts, evals, get-shit-done, plugin configs (installed list
and marketplace sources). Excludes credentials, runtime caches,
telemetry, session data, and plugin binary cache.

rules/golang/coding-style.md

@@ -0,0 +1,32 @@
+---
+paths:
+  - "**/*.go"
+  - "**/go.mod"
+  - "**/go.sum"
+---
+# 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.