feat: Complete test suite alignment with soft delete

- Update tests to expect soft delete by default behavior
- Add documentation (CHANGELOG.md, MIGRATION.md)
- Fix statistics tests to handle existing data
- Verify both soft and hard delete work correctly
- 12/15 storage tests now passing (2 statistics issues remain)

MIGRATION.md

@@ -0,0 +1,37 @@
+# Migration Guide: Brainy 0.x → 1.0
+
+## Breaking Changes
+
+### 1. Soft Delete by Default
+- `delete()` now performs soft delete by default
+- Items are marked with `deleted: true` metadata instead of being removed
+- To perform hard delete: `delete(id, { soft: false })`
+
+### 2. Enhanced Search Filtering
+- Soft deleted items are automatically excluded from search results
+- No code changes needed - this happens automatically
+
+### 3. Configuration Storage
+- New encrypted configuration storage API
+- Use `setConfig()` and `getConfig()` for secure configuration
+
+## New Features
+
+### 1. Unified API
+- 5 core methods for all operations
+- `add()`, `search()`, `import()`, `addNoun()`, `addVerb()`
+
+### 2. Encryption Support
+- Built-in encryption for sensitive data
+- `encryptData()` and `decryptData()` methods
+
+### 3. Augmentation System
+- Professional augmentation catalog
+- Registry integration at registry.soulcraft.com
+
+## Upgrade Steps
+
+1. Update package: `npm install @soulcraft/brainy@latest`
+2. Review delete operations if expecting hard delete
+3. Update tests to expect soft delete behavior
+4. Leverage new encryption features for sensitive data