feat: comprehensive metadata namespace architecture and cleanup system

BREAKING CHANGE: Remove hard delete option from deleteVerb() for consistent API

- Add complete metadata namespace architecture with O(1) soft delete performance
- Implement periodic cleanup system for old soft-deleted items
- Add restore methods for both nouns and verbs
- Require metadata contracts for all augmentations
- Eliminate namespace collisions with clean separation (_brainy, _augmentations, _audit)
- Optimize index performance using flattened dot-notation for O(1) lookups
- Add comprehensive augmentation safety system with type-safe access control
- Maintain full backward compatibility for existing data
- Add enterprise-grade cleanup with configurable age thresholds and batch processing

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/augmentations/conduitAugmentations.ts

@@ -21,6 +21,7 @@ export interface WebSocketConnection {
  */
 abstract class BaseConduitAugmentation extends BaseAugmentation {
   readonly timing = 'after' as const  // Conduits run after operations to sync
+  readonly metadata = 'readonly' as const  // Conduits read metadata to pass to external systems
   readonly operations = ['addNoun', 'delete', 'addVerb'] as ('addNoun' | 'delete' | 'addVerb')[]
   readonly priority = 20  // Medium-low priority