feat: complete OpenCode plugin support with hooks, tools, and commands

Major OpenCode integration overhaul:

- llms.txt: Comprehensive OpenCode documentation for LLMs (642 lines)
- .opencode/plugins/ecc-hooks.ts: All Claude Code hooks translated to OpenCode's plugin system
- .opencode/tools/*.ts: 3 custom tools (run-tests, check-coverage, security-audit)
- .opencode/commands/*.md: All 24 commands in OpenCode format
- .opencode/package.json: npm package structure for opencode-ecc
- .opencode/index.ts: Main plugin entry point

- Delete incorrect LIMITATIONS.md (hooks ARE supported via plugins)
- Rewrite MIGRATION.md with correct hook event mapping
- Update README.md OpenCode section to show full feature parity

OpenCode has 20+ events vs Claude Code's 3 phases:
- PreToolUse → tool.execute.before
- PostToolUse → tool.execute.after
- Stop → session.idle
- SessionStart → session.created
- SessionEnd → session.deleted
- Plus: file.edited, file.watcher.updated, permission.asked, todo.updated

- 12 agents: Full parity
- 24 commands: Full parity (+1 from original 23)
- 16 skills: Full parity
- Hooks: OpenCode has MORE (20+ events vs 3 phases)
- Custom Tools: 3 native OpenCode tools

The OpenCode configuration can now be:
1. Used directly: cd everything-claude-code && opencode
2. Installed via npm: npm install opencode-ecc

.opencode/commands/go-test.md

@@ -0,0 +1,131 @@
+---
+description: Go TDD workflow with table-driven tests
+agent: tdd-guide
+subtask: true
+---
+
+# Go Test Command
+
+Implement using Go TDD methodology: $ARGUMENTS
+
+## Your Task
+
+Apply test-driven development with Go idioms:
+
+1. **Define types** - Interfaces and structs
+2. **Write table-driven tests** - Comprehensive coverage
+3. **Implement minimal code** - Pass the tests
+4. **Benchmark** - Verify performance
+
+## TDD Cycle for Go
+
+### Step 1: Define Interface
+```go
+type Calculator interface {
+    Calculate(input Input) (Output, error)
+}
+
+type Input struct {
+    // fields
+}
+
+type Output struct {
+    // fields
+}
+```
+
+### Step 2: Table-Driven Tests
+```go
+func TestCalculate(t *testing.T) {
+    tests := []struct {
+        name    string
+        input   Input
+        want    Output
+        wantErr bool
+    }{
+        {
+            name:  "valid input",
+            input: Input{...},
+            want:  Output{...},
+        },
+        {
+            name:    "invalid input",
+            input:   Input{...},
+            wantErr: true,
+        },
+    }
+
+    for _, tt := range tests {
+        t.Run(tt.name, func(t *testing.T) {
+            got, err := Calculate(tt.input)
+            if (err != nil) != tt.wantErr {
+                t.Errorf("Calculate() error = %v, wantErr %v", err, tt.wantErr)
+                return
+            }
+            if !reflect.DeepEqual(got, tt.want) {
+                t.Errorf("Calculate() = %v, want %v", got, tt.want)
+            }
+        })
+    }
+}
+```
+
+### Step 3: Run Tests (RED)
+```bash
+go test -v ./...
+```
+
+### Step 4: Implement (GREEN)
+```go
+func Calculate(input Input) (Output, error) {
+    // Minimal implementation
+}
+```
+
+### Step 5: Benchmark
+```go
+func BenchmarkCalculate(b *testing.B) {
+    input := Input{...}
+    for i := 0; i < b.N; i++ {
+        Calculate(input)
+    }
+}
+```
+
+## Go Testing Commands
+
+```bash
+# Run all tests
+go test ./...
+
+# Run with verbose output
+go test -v ./...
+
+# Run with coverage
+go test -cover ./...
+
+# Run with race detector
+go test -race ./...
+
+# Run benchmarks
+go test -bench=. ./...
+
+# Generate coverage report
+go test -coverprofile=coverage.out ./...
+go tool cover -html=coverage.out
+```
+
+## Test File Organization
+
+```
+package/
+├── calculator.go       # Implementation
+├── calculator_test.go  # Tests
+├── testdata/           # Test fixtures
+│   └── input.json
+└── mock_test.go        # Mock implementations
+```
+
+---
+
+**TIP**: Use `testify/assert` for cleaner assertions, or stick with stdlib for simplicity.