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/tdd.md

@@ -1,66 +0,0 @@
----
-description: Enforce TDD workflow with 80%+ coverage
-agent: tdd-guide
-subtask: true
----
-
-# TDD Command
-
-Implement the following using strict test-driven development: $ARGUMENTS
-
-## TDD Cycle (MANDATORY)
-
-```
-RED → GREEN → REFACTOR → REPEAT
-```
-
-1. **RED**: Write a failing test FIRST
-2. **GREEN**: Write minimal code to pass the test
-3. **REFACTOR**: Improve code while keeping tests green
-4. **REPEAT**: Continue until feature complete
-
-## Your Task
-
-### Step 1: Define Interfaces (SCAFFOLD)
-- Define TypeScript interfaces for inputs/outputs
-- Create function signature with `throw new Error('Not implemented')`
-
-### Step 2: Write Failing Tests (RED)
-- Write tests that exercise the interface
-- Include happy path, edge cases, and error conditions
-- Run tests - verify they FAIL
-
-### Step 3: Implement Minimal Code (GREEN)
-- Write just enough code to make tests pass
-- No premature optimization
-- Run tests - verify they PASS
-
-### Step 4: Refactor (IMPROVE)
-- Extract constants, improve naming
-- Remove duplication
-- Run tests - verify they still PASS
-
-### Step 5: Check Coverage
-- Target: 80% minimum
-- 100% for critical business logic
-- Add more tests if needed
-
-## Coverage Requirements
-
-| Code Type | Minimum |
-|-----------|---------|
-| Standard code | 80% |
-| Financial calculations | 100% |
-| Authentication logic | 100% |
-| Security-critical code | 100% |
-
-## Test Types to Include
-
-- **Unit Tests**: Individual functions
-- **Edge Cases**: Empty, null, max values, boundaries
-- **Error Conditions**: Invalid inputs, network failures
-- **Integration Tests**: API endpoints, database operations
-
----
-
-**MANDATORY**: Tests must be written BEFORE implementation. Never skip the RED phase.