Add two-tier IP exemption system; fix scan button to use /api/exempt
- Add EXEMPT_FILE, readExemptions/saveExemptions/isExempt/addExemption/removeExemption
- Filter exempt IPs from scan results (still monitored by fail2ban)
- buildBanList() appends exempt entries with jail:'exempt'
- API: POST /api/exempt, DELETE /api/exempt/:ip, GET /api/exemptions
- Frontend: [EXEMPT] filter tab, exempt jail color, REMOVE/ARREST/THREAT actions
- Scan card [WHITELIST] button → [EXEMPT] calling /api/exempt (not ignoreip)
- Fix isWhitelisted() to read only jail.local with proper CIDR matching
- Fix readIgnoreIP() regex: \s* → [ \t]* to prevent cross-line capture
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>