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/testing.md

@@ -0,0 +1,31 @@
+---
+paths:
+  - "**/*.go"
+  - "**/go.mod"
+  - "**/go.sum"
+---
+# Go Testing
+
+> This file extends [common/testing.md](../common/testing.md) with Go specific content.
+
+## Framework
+
+Use the standard `go test` with **table-driven tests**.
+
+## Race Detection
+
+Always run with the `-race` flag:
+
+```bash
+go test -race ./...
+```
+
+## Coverage
+
+```bash
+go test -cover ./...
+```
+
+## Reference
+
+See skill: `golang-testing` for detailed Go testing patterns and helpers.