Add SQLite database schema and documentation

Added complete database schema for Post-ERG thesis archive:
- schema.sql with full relational database structure
- README.md with schema documentation and usage examples
- SETUP.md with comprehensive setup and maintenance guide
- posterg_fiche-technique.md with technical specifications
- Database_TFE_test.csv and .ods with example data

Database features:
- Normalized relational schema (3NF)
- Support for multiple authors, supervisors, languages, formats, keywords
- Publication workflow (submission → defense → jury review → publication)
- Access control (Libre/Interne/Interdit)
- File attachments tracking
- Predefined reference tables for orientations, AP programs, finalities
- Views for simplified querying
- Automatic timestamps and cascade deletes

formulaire/.htaccess

@@ -0,0 +1,36 @@
+# Security headers
+<IfModule mod_headers.c>
+    # Prevent clickjacking
+    Header always set X-Frame-Options "SAMEORIGIN"
+
+    # Prevent MIME type sniffing
+    Header always set X-Content-Type-Options "nosniff"
+
+    # Enable XSS protection
+    Header always set X-XSS-Protection "1; mode=block"
+
+    # Referrer policy
+    Header always set Referrer-Policy "strict-origin-when-cross-origin"
+
+    # Content Security Policy (adjust as needed)
+    Header always set Content-Security-Policy "default-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:;"
+</IfModule>
+
+# Prevent directory listing
+Options -Indexes
+
+# Protect sensitive files
+<FilesMatch "^\.">
+    Require all denied
+</FilesMatch>
+
+<FilesMatch "(composer\.(json|lock)|error\.log)$">
+    Require all denied
+</FilesMatch>
+
+# PHP security settings (if .htaccess can override)
+<IfModule mod_php.c>
+    php_flag display_errors Off
+    php_flag log_errors On
+    php_value error_log error.log
+</IfModule>