Revert "feat(ecc): prune plugin 43→12 items, promote 7 rules to .claude/rules/ (#245)"

This reverts commit 1bd68ff534.

rules/golang/patterns.md

@@ -0,0 +1,45 @@
+---
+paths:
+  - "**/*.go"
+  - "**/go.mod"
+  - "**/go.sum"
+---
+# Go Patterns
+
+> This file extends [common/patterns.md](../common/patterns.md) with Go specific content.
+
+## Functional Options
+
+```go
+type Option func(*Server)
+
+func WithPort(port int) Option {
+    return func(s *Server) { s.port = port }
+}
+
+func NewServer(opts ...Option) *Server {
+    s := &Server{port: 8080}
+    for _, opt := range opts {
+        opt(s)
+    }
+    return s
+}
+```
+
+## Small Interfaces
+
+Define interfaces where they are used, not where they are implemented.
+
+## Dependency Injection
+
+Use constructor functions to inject dependencies:
+
+```go
+func NewUserService(repo UserRepository, logger Logger) *UserService {
+    return &UserService{repo: repo, logger: logger}
+}
+```
+
+## Reference
+
+See skill: `golang-patterns` for comprehensive Go patterns including concurrency, error handling, and package organization.