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-review.md

@@ -0,0 +1,71 @@
+---
+description: Go code review for idiomatic patterns
+agent: go-reviewer
+subtask: true
+---
+
+# Go Review Command
+
+Review Go code for idiomatic patterns and best practices: $ARGUMENTS
+
+## Your Task
+
+1. **Analyze Go code** for idioms and patterns
+2. **Check concurrency** - goroutines, channels, mutexes
+3. **Review error handling** - proper error wrapping
+4. **Verify performance** - allocations, bottlenecks
+
+## Review Checklist
+
+### Idiomatic Go
+- [ ] Package naming (lowercase, no underscores)
+- [ ] Variable naming (camelCase, short)
+- [ ] Interface naming (ends with -er)
+- [ ] Error naming (starts with Err)
+
+### Error Handling
+- [ ] Errors are checked, not ignored
+- [ ] Errors wrapped with context (`fmt.Errorf("...: %w", err)`)
+- [ ] Sentinel errors used appropriately
+- [ ] Custom error types when needed
+
+### Concurrency
+- [ ] Goroutines properly managed
+- [ ] Channels buffered appropriately
+- [ ] No data races (use `-race` flag)
+- [ ] Context passed for cancellation
+- [ ] WaitGroups used correctly
+
+### Performance
+- [ ] Avoid unnecessary allocations
+- [ ] Use `sync.Pool` for frequent allocations
+- [ ] Prefer value receivers for small structs
+- [ ] Buffer I/O operations
+
+### Code Organization
+- [ ] Small, focused packages
+- [ ] Clear dependency direction
+- [ ] Internal packages for private code
+- [ ] Godoc comments on exports
+
+## Report Format
+
+### Idiomatic Issues
+- [file:line] Issue description
+  Suggestion: How to fix
+
+### Error Handling Issues
+- [file:line] Issue description
+  Suggestion: How to fix
+
+### Concurrency Issues
+- [file:line] Issue description
+  Suggestion: How to fix
+
+### Performance Issues
+- [file:line] Issue description
+  Suggestion: How to fix
+
+---
+
+**TIP**: Run `go vet` and `staticcheck` for additional automated checks.