Plugin Expansion — Extend ccgs-hooks.ts and add new plugins

[striderZA]

Summary

Expand the plugin system beyond the single ccgs-hooks.ts plugin. Add lifecycle hooks, validators, and automation plugins.

Scope

Improve ccgs-hooks.ts

• Audit existing hook implementations for correctness
• Add error handling and logging
• Ensure hooks fire on correct lifecycle events

New Plugins

• pre-commit-validator.ts: Validates agent/skill/rule file structure before commits
• output-validator.ts: Checks agent outputs match expected schemas during execution
• drift-detector.ts: Detects when agent/skill files deviate from templates
• changelog-generator.ts: Auto-generates CHANGELOG from conventional commits

Plugin Architecture

• Consistent plugin interface (register, execute, teardown)
• Plugin config in opencode.json
• Plugin test harness

Acceptance Criteria

• ccgs-hooks.ts audited, errors handled, logged
• pre-commit-validator.ts created and functional
• At least 1 more plugin from the list implemented
• Plugin architecture documented
• Plugin tests passing