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.

.opencode/commands/go-review.md

@@ -1,71 +0,0 @@
----
-description: Go code review for idiomatic patterns
-agent: go-reviewer
-subtask: true
----
-
-# Go Review Command
-
-Review Go code for idiomatic patterns and best practices: $ARGUMENTS
-
-## Your Task
-
-1. **Analyze Go code** for idioms and patterns
-2. **Check concurrency** - goroutines, channels, mutexes
-3. **Review error handling** - proper error wrapping
-4. **Verify performance** - allocations, bottlenecks
-
-## Review Checklist
-
-### Idiomatic Go
-- [ ] Package naming (lowercase, no underscores)
-- [ ] Variable naming (camelCase, short)
-- [ ] Interface naming (ends with -er)
-- [ ] Error naming (starts with Err)
-
-### Error Handling
-- [ ] Errors are checked, not ignored
-- [ ] Errors wrapped with context (`fmt.Errorf("...: %w", err)`)
-- [ ] Sentinel errors used appropriately
-- [ ] Custom error types when needed
-
-### Concurrency
-- [ ] Goroutines properly managed
-- [ ] Channels buffered appropriately
-- [ ] No data races (use `-race` flag)
-- [ ] Context passed for cancellation
-- [ ] WaitGroups used correctly
-
-### Performance
-- [ ] Avoid unnecessary allocations
-- [ ] Use `sync.Pool` for frequent allocations
-- [ ] Prefer value receivers for small structs
-- [ ] Buffer I/O operations
-
-### Code Organization
-- [ ] Small, focused packages
-- [ ] Clear dependency direction
-- [ ] Internal packages for private code
-- [ ] Godoc comments on exports
-
-## Report Format
-
-### Idiomatic Issues
-- [file:line] Issue description
-  Suggestion: How to fix
-
-### Error Handling Issues
-- [file:line] Issue description
-  Suggestion: How to fix
-
-### Concurrency Issues
-- [file:line] Issue description
-  Suggestion: How to fix
-
-### Performance Issues
-- [file:line] Issue description
-  Suggestion: How to fix
-
----
-
-**TIP**: Run `go vet` and `staticcheck` for additional automated checks.