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

shared/config.php

@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * Configuration for Post-ERG thesis database
+ * Central location for database paths and environment settings
+ */
+
+// Database paths relative to repository root
+define('DB_ROOT', __DIR__ . '/..');
+
+// Test database (used in development)
+define('DB_TEST_PATH', DB_ROOT . '/database/test.db');
+
+// Production database (used on server)
+define('DB_PROD_PATH', DB_ROOT . '/database/posterg.db');
+
+/**
+ * Determine which database to use
+ * Checks environment variable DB_ENV, defaults to auto-detection
+ *
+ * Set DB_ENV in your environment:
+ * - export DB_ENV=test     # Force test database
+ * - export DB_ENV=prod     # Force production database
+ *
+ * Auto-detection logic:
+ * - If test.db exists, use it (development)
+ * - Otherwise use posterg.db (production)
+ */
+function getDatabasePath() {
+    // Allow explicit override via environment variable
+    $env = getenv('DB_ENV');
+
+    if ($env === 'test') {
+        return DB_TEST_PATH;
+    }
+
+    if ($env === 'prod') {
+        return DB_PROD_PATH;
+    }
+
+    // Auto-detect: prefer test database if it exists
+    if (file_exists(DB_TEST_PATH)) {
+        return DB_TEST_PATH;
+    }
+
+    // Default to production database
+    return DB_PROD_PATH;
+}
+
+/**
+ * Check if running in test/development mode
+ */
+function isTestMode() {
+    return getDatabasePath() === DB_TEST_PATH;
+}