feat: add entity exposure detection (v0.3.0)

Implement entity exposure detection to prevent domain entities
from leaking to API responses. Detects when controllers/routes
return domain entities instead of DTOs.

Features:
- EntityExposure value object with detailed suggestions
- IEntityExposureDetector interface in domain layer
- EntityExposureDetector implementation in infrastructure
- Integration into AnalyzeProject use case
- CLI display with helpful suggestions
- 24 comprehensive unit tests (98% coverage)
- Examples for bad and good patterns

Detection scope:
- Infrastructure layer only (controllers, routes, handlers, resolvers, gateways)
- Identifies PascalCase entities without Dto/Request/Response suffixes
- Parses async methods with Promise<T> return types
- Provides step-by-step remediation suggestions

Test coverage:
- EntityExposureDetector: 98.07%
- Overall project: 90.6% statements, 83.97% branches
- 218 tests passing

BREAKING CHANGE: Version bump to 0.3.0

packages/guardian/src/shared/constants/rules.ts

@@ -7,6 +7,7 @@ export const RULES = {
     CIRCULAR_DEPENDENCY: "circular-dependency",
     NAMING_CONVENTION: "naming-convention",
     FRAMEWORK_LEAK: "framework-leak",
+    ENTITY_EXPOSURE: "entity-exposure",
 } as const
 
 /**