feat: add aggregate boundary validation (v0.7.0)

Implement DDD aggregate boundary validation to detect and prevent direct
entity references across aggregate boundaries.

Features:
- Detect direct entity imports between aggregates
- Allow only ID or Value Object references
- Support multiple folder structures (domain/aggregates/*, domain/*, domain/entities/*)
- Filter allowed imports (value-objects, events, repositories, services)
- Critical severity level for violations
- 41 comprehensive tests with 92.55% coverage
- CLI output with detailed suggestions
- Examples of good and bad patterns

Breaking changes: None
Backwards compatible: Yes

packages/guardian/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@samiyev/guardian",
-    "version": "0.6.4",
+    "version": "0.7.0",
     "description": "Research-backed code quality guardian for AI-assisted development. Detects hardcodes, circular deps, framework leaks, entity exposure, and 8 architecture violations. Enforces Clean Architecture/DDD principles. Works with GitHub Copilot, Cursor, Windsurf, Claude, ChatGPT, Cline, and any AI coding tool.",
     "keywords": [
         "puaros",