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

ECC community plugin pruning: removed 530+ non-essential files
(.cursor/, .opencode/, docs/ja-JP, docs/zh-CN, docs/zh-TW,
language-specific skills/agents/rules). Retained 4 agents,
3 commands, 5 skills. Promoted 13 rule files (8 common + 5
typescript) to .claude/rules/ for CC native loading. Extracted
reusable patterns to EXTRACTED-PATTERNS.md.

docs/zh-CN/rules/golang/security.md

@@ -1,28 +0,0 @@
-# Go 安全
-
-> 此文件基于 [common/security.md](../common/security.md) 扩展了 Go 特定内容。
-
-## 密钥管理
-
-```go
-apiKey := os.Getenv("OPENAI_API_KEY")
-if apiKey == "" {
-    log.Fatal("OPENAI_API_KEY not configured")
-}
-```
-
-## 安全扫描
-
-* 使用 **gosec** 进行静态安全分析：
-  ```bash
-  gosec ./...
-  ```
-
-## 上下文与超时
-
-始终使用 `context.Context` 进行超时控制：
-
-```go
-ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
-defer cancel()
-```