security(p0): mark CORS config and input validation as completed; env management and gitignore confirmed; docs updated

TODO.md

@@ -10,25 +10,25 @@
 - [x] **URGENT**: Remove `.env` file from git repository
 - [x] **URGENT**: Generate new SECRET_KEY (32+ character random string)
 - [x] **URGENT**: Change default admin password from `admin123` to secure password
-- [ ] **URGENT**: Implement proper environment variable management
-- [ ] **URGENT**: Add `.env` to `.gitignore` and commit
-- [ ] **URGENT**: Document secret rotation procedures
+- [x] **URGENT**: Implement proper environment variable management
+- [x] **URGENT**: Add `.env` to `.gitignore` and commit
+- [x] **URGENT**: Document secret rotation procedures
 
 **Impact**: Complete system compromise if repository accessed by unauthorized users
 
 ### **Fix CORS Configuration**
-- [ ] **URGENT**: Change `allow_origins=["*"]` to specific domains in `app/main.py:65`
-- [ ] **URGENT**: Configure proper CORS headers for production
+- [x] **URGENT**: Change `allow_origins=["*"]` to specific domains in `app/main.py:65`
+- [x] **URGENT**: Configure proper CORS headers for production
 - [ ] **URGENT**: Test CORS configuration with frontend domains
 
 **Impact**: Prevents XSS, CSRF, and data theft vulnerabilities
 
 ### **Implement Input Validation**
-- [ ] **URGENT**: Add file type validation for upload endpoints
-- [ ] **URGENT**: Add file size limits to prevent DoS attacks
-- [ ] **URGENT**: Implement path traversal protection in file operations
-- [ ] **URGENT**: Add CSV import data validation and sanitization
-- [ ] **URGENT**: Validate all user inputs with Pydantic schemas
+- [x] **URGENT**: Add file type validation for upload endpoints
+- [x] **URGENT**: Add file size limits to prevent DoS attacks
+- [x] **URGENT**: Implement path traversal protection in file operations
+- [x] **URGENT**: Add CSV import data validation and sanitization
+- [x] **URGENT**: Validate all user inputs with Pydantic schemas
 
 **Impact**: Prevents file upload attacks and data injection