feat(prospecting): implement security audit pipeline (Workstream 2A)

Complete security audit integration into the enrichment pipeline:

Backend:
- SecurityAuditService with 7 passive checks: HTTPS, SSL cert, security
  headers, exposed files, cookies, server info, technology detection
- Constants file with SECURITY_HEADERS, EXPOSED_PATHS, SEVERITY_SCORES
- SecurityAuditResponse schema with JSON field validators + aliases
- Endpoints: POST /security-audit/{id}, POST /security-audit/batch
- Added to full_enrichment pipeline (Step 5, before scoring)
- get_pending_security_audit() query in prospect_service

Frontend:
- Security tab on prospect detail page with grade badge (A+ to F),
  score/100, severity counts, HTTPS/SSL status, missing headers,
  exposed files, technologies, and full findings list
- "Run Security Audit" button with loading state
- "Security Audit" batch button on scan-jobs page

Tested on batirenovation-strasbourg.fr: Grade D (50/100), 11 issues
found (missing headers, exposed wp-login, server version disclosure).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/prospecting/services/security_audit_constants.py

@@ -0,0 +1,75 @@
+# app/modules/prospecting/services/security_audit_constants.py
+"""
+Constants for security audit checks.
+
+Structural data used by SecurityAuditService. Translations for report
+generation are kept in the standalone script (scripts/security-audit/audit.py)
+until Phase 2B (report service) migrates them.
+"""
+
+# Severity scores — deducted from a starting score of 100
+SEVERITY_SCORES = {
+    "critical": 15,
+    "high": 10,
+    "medium": 5,
+    "low": 2,
+    "info": 0,
+}
+
+# Security headers to check and their severity if missing
+SECURITY_HEADERS = {
+    "Strict-Transport-Security": {"severity": "high", "impact": "MITM attacks, session hijacking via HTTP downgrade"},
+    "Content-Security-Policy": {"severity": "high", "impact": "XSS attacks, script injection, data theft"},
+    "X-Frame-Options": {"severity": "medium", "impact": "Clickjacking attacks via invisible iframes"},
+    "X-Content-Type-Options": {"severity": "medium", "impact": "MIME type confusion, content injection"},
+    "Referrer-Policy": {"severity": "low", "impact": "URL parameter leakage to third parties"},
+    "Permissions-Policy": {"severity": "low", "impact": "Unrestricted browser API access (camera, mic, location)"},
+    "X-XSS-Protection": {"severity": "info", "impact": "Legacy XSS filter not configured"},
+}
+
+# Paths to check for exposed sensitive files/directories
+EXPOSED_PATHS = [
+    ("/.env", "Environment file (database passwords, API keys)", "critical"),
+    ("/.git/config", "Git repository (full source code)", "critical"),
+    ("/.git/HEAD", "Git repository HEAD", "critical"),
+    ("/.htpasswd", "Password file", "critical"),
+    ("/wp-admin/", "WordPress admin panel", "high"),
+    ("/wp-login.php", "WordPress login page", "high"),
+    ("/administrator/", "Joomla admin panel", "high"),
+    ("/admin/", "Admin panel", "high"),
+    ("/admin/login", "Admin login page", "high"),
+    ("/phpmyadmin/", "phpMyAdmin (database manager)", "high"),
+    ("/backup/", "Backup directory", "high"),
+    ("/backup.zip", "Backup archive", "high"),
+    ("/backup.sql", "Database backup", "high"),
+    ("/db.sql", "Database dump", "high"),
+    ("/dump.sql", "Database dump", "high"),
+    ("/.htaccess", "Server configuration", "medium"),
+    ("/web.config", "IIS configuration", "medium"),
+    ("/server-status", "Apache server status", "medium"),
+    ("/server-info", "Apache server info", "medium"),
+    ("/info.php", "PHP info page", "medium"),
+    ("/phpinfo.php", "PHP info page", "medium"),
+    ("/graphql", "GraphQL endpoint", "medium"),
+    ("/debug/", "Debug endpoint", "medium"),
+    ("/elmah.axd", ".NET error log", "medium"),
+    ("/trace.axd", ".NET trace log", "medium"),
+    ("/readme.html", "CMS readme (reveals version)", "low"),
+    ("/license.txt", "CMS license (reveals version)", "low"),
+    ("/CHANGELOG.md", "Changelog (reveals version)", "low"),
+    ("/robots.txt", "Robots file", "info"),
+    ("/.well-known/security.txt", "Security contact file", "info"),
+    ("/sitemap.xml", "Sitemap", "info"),
+    ("/crossdomain.xml", "Flash cross-domain policy", "low"),
+    ("/api/", "API endpoint", "info"),
+]
+
+# Paths that are admin panels (separate severity logic)
+ADMIN_PATHS = {"/wp-admin/", "/wp-login.php", "/administrator/", "/admin/", "/admin/login"}
+
+# Robots.txt disallow patterns that may reveal sensitive areas
+ROBOTS_SENSITIVE_PATTERNS = [
+    "admin", "backup", "private", "secret", "staging",
+    "test", "dev", "internal", "api", "config",
+    "database", "panel", "dashboard", "login", "cgi-bin",
+]