fix: spurious health alerts, show rotated logs, clear history button

app.py:
- Alert logic now checks status.running (container up/down) instead of healthy
  (which requires connectivity tests) — services are only alerted when actually down
- Add POST /api/health/history/clear endpoint to reset history + alert counters

log_manager.py:
- get_all_log_file_infos: include rotated backup files (*.log.1, *.log.2 ...) in listing,
  marked with backup=true so UI can dim them and hide rotate button

api.js: add monitoringAPI.clearHealthHistory

Logs page:
- Health History: add Clear button with confirmation
- File panel: show full filename (including .log.1 backups), explain host path and naming,
  hide rotate button for backup files

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webui/src/services/api.js

@@ -184,6 +184,7 @@ export const healthAPI = {
 export const monitoringAPI = {
   getBackendLogs: (lines = 100) => api.get('/api/logs', { params: { lines } }),
   getHealthHistory: () => api.get('/api/health/history'),
+  clearHealthHistory: () => api.post('/api/health/history/clear'),
 };
 
 // Logs API