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/code-review.md

@@ -0,0 +1,68 @@
+---
+description: Review code for quality, security, and maintainability
+agent: code-reviewer
+subtask: true
+---
+
+# Code Review Command
+
+Review code changes for quality, security, and maintainability: $ARGUMENTS
+
+## Your Task
+
+1. **Get changed files**: Run `git diff --name-only HEAD`
+2. **Analyze each file** for issues
+3. **Generate structured report**
+4. **Provide actionable recommendations**
+
+## Check Categories
+
+### Security Issues (CRITICAL)
+- [ ] Hardcoded credentials, API keys, tokens
+- [ ] SQL injection vulnerabilities
+- [ ] XSS vulnerabilities
+- [ ] Missing input validation
+- [ ] Insecure dependencies
+- [ ] Path traversal risks
+- [ ] Authentication/authorization flaws
+
+### Code Quality (HIGH)
+- [ ] Functions > 50 lines
+- [ ] Files > 800 lines
+- [ ] Nesting depth > 4 levels
+- [ ] Missing error handling
+- [ ] console.log statements
+- [ ] TODO/FIXME comments
+- [ ] Missing JSDoc for public APIs
+
+### Best Practices (MEDIUM)
+- [ ] Mutation patterns (use immutable instead)
+- [ ] Unnecessary complexity
+- [ ] Missing tests for new code
+- [ ] Accessibility issues (a11y)
+- [ ] Performance concerns
+
+### Style (LOW)
+- [ ] Inconsistent naming
+- [ ] Missing type annotations
+- [ ] Formatting issues
+
+## Report Format
+
+For each issue found:
+
+```
+**[SEVERITY]** file.ts:123
+Issue: [Description]
+Fix: [How to fix]
+```
+
+## Decision
+
+- **CRITICAL or HIGH issues**: Block commit, require fixes
+- **MEDIUM issues**: Recommend fixes before merge
+- **LOW issues**: Optional improvements
+
+---
+
+**IMPORTANT**: Never approve code with security vulnerabilities!