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/test-coverage.md

@@ -1,80 +0,0 @@
----
-description: Analyze and improve test coverage
-agent: tdd-guide
-subtask: true
----
-
-# Test Coverage Command
-
-Analyze test coverage and identify gaps: $ARGUMENTS
-
-## Your Task
-
-1. **Run coverage report**: `npm test -- --coverage`
-2. **Analyze results** - Identify low coverage areas
-3. **Prioritize gaps** - Critical code first
-4. **Generate missing tests** - For uncovered code
-
-## Coverage Targets
-
-| Code Type | Target |
-|-----------|--------|
-| Standard code | 80% |
-| Financial logic | 100% |
-| Auth/security | 100% |
-| Utilities | 90% |
-| UI components | 70% |
-
-## Coverage Report Analysis
-
-### Summary
-```
-File           | % Stmts | % Branch | % Funcs | % Lines
----------------|---------|----------|---------|--------
-All files      |   XX    |    XX    |   XX    |   XX
-```
-
-### Low Coverage Files
-[Files below target, prioritized by criticality]
-
-### Uncovered Lines
-[Specific lines that need tests]
-
-## Test Generation
-
-For each uncovered area:
-
-### [Function/Component Name]
-
-**Location**: `src/path/file.ts:123`
-
-**Coverage Gap**: [description]
-
-**Suggested Tests**:
-```typescript
-describe('functionName', () => {
-  it('should [expected behavior]', () => {
-    // Test code
-  })
-
-  it('should handle [edge case]', () => {
-    // Edge case test
-  })
-})
-```
-
-## Coverage Improvement Plan
-
-1. **Critical** (add immediately)
-   - [ ] file1.ts - Auth logic
-   - [ ] file2.ts - Payment handling
-
-2. **High** (add this sprint)
-   - [ ] file3.ts - Core business logic
-
-3. **Medium** (add when touching file)
-   - [ ] file4.ts - Utilities
-
----
-
-**IMPORTANT**: Coverage is a metric, not a goal. Focus on meaningful tests, not just hitting numbers.