docs: update npm commands to bun in README and documentation files

- Replace npm install with bun install
- Replace npm start/test/build with bun equivalents
- Update deployment and testing documentation
- Maintain consistency with project's bun-first approach

🤖 Generated with [AI Assistant]

Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

SECURITY_AUDIT_REPORT.md

@@ -71,10 +71,10 @@ router.get("/:id", auth, async (req, res) => {
 **Remediation:**
 ```bash
 # Backend
-cd backend && npm update axios
+cd backend && bun update axios
 
 # Frontend
-cd frontend && npm update axios
+cd frontend && bun update axios
 ```
 
 **Fix Available:** Yes - Update to axios >= 1.12.0
@@ -212,7 +212,7 @@ User-generated content is rendered directly without sanitization. While React es
 Install and use DOMPurify for content sanitization:
 
 ```bash
-npm install dompurify
+bun install dompurify
 ```
 
 ```javascript
@@ -331,7 +331,7 @@ const salt = await bcrypt.genSalt(12); // Increase to 12 or 14 rounds
 If using cookies (recommended over localStorage):
 
 ```bash
-npm install csurf
+bun install csurf
 ```
 
 ```javascript
@@ -840,8 +840,8 @@ const posts = await Post.find()
 
 ### Recommendation:
 ```bash
-cd backend && npm audit fix
-cd frontend && npm audit fix
+cd backend && bun audit fix
+cd frontend && bun audit fix
 ```
 
 ---
@@ -859,7 +859,7 @@ cd frontend && npm audit fix
 ### Automated Testing Recommendations:
 1. Set up OWASP ZAP or Burp Suite automated scanning
 2. Implement security test suite with Jest/Supertest
-3. Add pre-commit hook with `npm audit`
+3. Add pre-commit hook with `bun audit`
 4. Set up Snyk or similar for continuous dependency monitoring
 
 ---
@@ -904,10 +904,10 @@ cd frontend && npm audit fix
 ```yaml
 # .github/workflows/security.yml
 - name: Security Audit
-  run: npm audit --audit-level=moderate
+  run: bun audit --audit-level=moderate
 
 - name: SAST Scan
-  run: npm run lint:security
+  run: bun run lint:security
 ```
 
 ### 3. Environment-Specific Configurations