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.

contexts/review.md

@@ -1,22 +0,0 @@
-# Code Review Context
-
-Mode: PR review, code analysis
-Focus: Quality, security, maintainability
-
-## Behavior
-- Read thoroughly before commenting
-- Prioritize issues by severity (critical > high > medium > low)
-- Suggest fixes, don't just point out problems
-- Check for security vulnerabilities
-
-## Review Checklist
-- [ ] Logic errors
-- [ ] Edge cases
-- [ ] Error handling
-- [ ] Security (injection, auth, secrets)
-- [ ] Performance
-- [ ] Readability
-- [ ] Test coverage
-
-## Output Format
-Group findings by file, severity first