Restructure repository and implement secure search feature

Phase 1: Consolidate shared infrastructure
- Create shared/ directory for common code
- Consolidate Database.php from front-backend and formulaire into unified shared/Database.php
  - Smart path detection for test.db vs posterg.db
  - Secure search with wildcard escaping and input validation
  - Support both singleton and direct instantiation patterns
  - Full CRUD methods for admin functionality
- Move RateLimit.php to shared/ (30 requests/min)
- Update all require paths across apps to use shared/

Phase 2: Reorganize directory structure
- Rename front-backend/ → apps/public/
- Rename formulaire/ → apps/admin/
- Rename db/ → database/
- Update all file paths for new structure
- Create root .gitignore excluding databases, cache, logs

Implement secure search feature
- Add apps/public/search.php with full-text search across theses
- Search filters: query, year, orientation, AP program, keywords
- Security features:
  - SQL injection prevention (prepared statements)
  - Wildcard injection prevention (escape % and _)
  - Input validation (max 200 chars, year range 1900-2100)
  - Rate limiting (30 req/min per IP)
  - Pagination limited to 100 results/page
  - XSS protection (htmlspecialchars on output)

Add comprehensive test suite
- Create apps/public/tests/ with proper structure
  - tests/Integration/SearchTest.php - 12 search scenarios
  - tests/Security/SecurityTest.php - vulnerability testing
  - tests/Unit/RateLimitTest.php - rate limit behavior
- Create database/fixtures/CreateTestDatabase.php
- Add apps/public/run-tests.php test runner
- All tests passing (4/4 suites)

Update deployment configuration
- Rename justfile 'sync' recipe to 'deploy'
- Create deploy group with separate deploy-public and deploy-admin
- Add test-deploy recipe for test database
- Exclude *.db, tests/, cache/, *.md from production deploy
- Deploy shared/ to both public and admin locations

Stats: +4482 insertions, -654 deletions across 72 files

apps/public/tests/README.md

@@ -0,0 +1,108 @@
+# Tests Directory
+
+This directory contains all tests for the front-backend application.
+
+## Structure
+
+```
+tests/
+├── Fixtures/           # Test data and setup scripts
+│   └── CreateTestDatabase.php
+├── Integration/        # Integration tests (multiple components)
+│   └── SearchTest.php
+├── Security/          # Security-focused tests
+│   └── SecurityTest.php
+└── Unit/              # Unit tests (individual methods)
+    └── RateLimitTest.php
+```
+
+## Running Tests
+
+### Run All Tests
+```bash
+php run-tests.php
+```
+
+### Run Individual Tests
+```bash
+# Setup test database first
+php tests/Fixtures/CreateTestDatabase.php
+
+# Run specific test
+php tests/Integration/SearchTest.php
+php tests/Security/SecurityTest.php
+php tests/Unit/RateLimitTest.php
+```
+
+## Test Suites
+
+### Fixtures
+Test data setup and database initialization.
+
+**CreateTestDatabase.php**
+- Creates test.db with sample theses
+- Populates with 6 sample records
+- Includes authors, supervisors, keywords
+
+### Integration Tests
+Test multiple components working together.
+
+**SearchTest.php**
+- Tests full search functionality
+- Tests filtering (year, orientation, AP, keywords)
+- Tests pagination
+- Tests combined filters
+
+### Security Tests
+Verify security measures are working.
+
+**SecurityTest.php**
+- Wildcard injection prevention
+- Input length validation
+- Year range validation
+- SQL injection prevention
+- Pagination limits
+
+### Unit Tests
+Test individual components in isolation.
+
+**RateLimitTest.php**
+- Rate limit enforcement
+- Request tracking
+- Reset time calculation
+- Header generation
+
+## Expected Results
+
+All tests should pass:
+```
+✅ PASSED - Fixtures/CreateTestDatabase.php
+✅ PASSED - Integration/SearchTest.php
+✅ PASSED - Security/SecurityTest.php
+✅ PASSED - Unit/RateLimitTest.php
+```
+
+## Deployment
+
+**Tests are NOT deployed to production.**
+
+The deployment configuration (`justfile`) excludes:
+- `tests/` directory
+- `*.db` files
+- Cache directory
+- Documentation files
+
+## Future Migration to PHPUnit
+
+This directory structure is compatible with PHPUnit. To migrate:
+
+1. Install PHPUnit:
+   ```bash
+   composer require --dev phpunit/phpunit
+   ```
+
+2. Convert test files to PHPUnit format
+3. Add `phpunit.xml` configuration
+4. Run with: `composer test`
+
+See `TESTING_BEST_PRACTICES.md` for details.