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

This reverts commit 1bd68ff534.

.opencode/commands/tdd.md

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+---
+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.