feat: add severity-based sorting and filtering for violations (v0.5.2)

- Add CRITICAL/HIGH/MEDIUM/LOW severity levels to all violations
- Sort violations by severity automatically (most critical first)
- Add CLI flags: --min-severity and --only-critical
- Group violations by severity in CLI output with color-coded headers
- Update all violation interfaces to include severity field
- Maintain 90%+ test coverage with all tests passing
- Update CHANGELOG.md, ROADMAP.md, and package version to 0.5.2

packages/guardian/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@samiyev/guardian",
-    "version": "0.5.1",
+    "version": "0.5.2",
     "description": "Code quality guardian for vibe coders and enterprise teams - catch hardcodes, architecture violations, and circular deps. Enforce Clean Architecture at scale. Works with Claude, GPT, Copilot.",
     "keywords": [
         "puaros",