refactor: replace 'any' types with proper TypeScript interfaces

Major type safety improvements throughout the codebase:

- Updated DEFAULT_CONFIG version to 4.2
- Replaced 'any' with proper types in systemd.ts:
  * displaySingleUpsStatus now uses IUpsConfig and NupstSnmp types
  * Fixed legacy config handling to use proper IUpsConfig format
  * Removed inline 'any' type annotations

- Replaced 'any' with proper types in daemon.ts:
  * emergencyUps now properly typed as { ups: IUpsConfig, status: ISnmpUpsStatus }
  * Exported IUpsStatus interface for reuse
  * Added ISnmpUpsStatus import to disambiguate from daemon's IUpsStatus

- Replaced 'any' with Record<string, unknown> in migration system:
  * Updated BaseMigration abstract class signatures
  * Updated MigrationRunner.run() signature
  * Updated migration-v4.0-to-v4.1.ts to use proper types
  * Migrations use Record<string, unknown> because they deal with
    unknown config schemas that are being upgraded

Benefits:
- TypeScript now catches type errors at compile time
- Would have caught the ups.thresholds bug earlier
- Better IDE autocomplete and type checking
- More maintainable and self-documenting code

ts/systemd.ts

@@ -1,7 +1,8 @@
 import process from 'node:process';
 import { promises as fs } from 'node:fs';
 import { execSync } from 'node:child_process';
-import { NupstDaemon } from './daemon.ts';
+import { NupstDaemon, type IUpsConfig } from './daemon.ts';
+import { NupstSnmp } from './snmp/manager.ts';
 import { logger } from './logger.ts';
 import { theme, symbols, getBatteryColor, getRuntimeColor, formatPowerStatus } from './colors.ts';
 
@@ -277,14 +278,23 @@ WantedBy=multi-user.target
           await this.displaySingleUpsStatus(ups, snmp);
         }
       } else if (config.snmp) {
-        // Legacy single UPS configuration
+        // Legacy single UPS configuration (v1/v2 format)
         logger.info('UPS Devices (1):');
-        const legacyUps = {
+        const legacyUps: IUpsConfig = {
           id: 'default',
           name: 'Default UPS',
           snmp: config.snmp,
-          thresholds: config.thresholds,
           groups: [],
+          actions: config.thresholds
+            ? [
+                {
+                  type: 'shutdown',
+                  thresholds: config.thresholds,
+                  triggerMode: 'onlyThresholds',
+                  shutdownDelay: 5,
+                },
+              ]
+            : [],
         };
 
         await this.displaySingleUpsStatus(legacyUps, snmp);
@@ -307,7 +317,7 @@ WantedBy=multi-user.target
    * @param ups UPS configuration
    * @param snmp SNMP manager
    */
-  private async displaySingleUpsStatus(ups: any, snmp: any): Promise<void> {
+  private async displaySingleUpsStatus(ups: IUpsConfig, snmp: NupstSnmp): Promise<void> {
     try {
       // Create a test config with a short timeout
       const testConfig = {
@@ -332,7 +342,7 @@ WantedBy=multi-user.target
       const batteryColor = getBatteryColor(status.batteryCapacity);
 
       // Get threshold from actions (if any action has thresholds defined)
-      const actionWithThresholds = ups.actions?.find((action: any) => action.thresholds);
+      const actionWithThresholds = ups.actions?.find((action) => action.thresholds);
       const batteryThreshold = actionWithThresholds?.thresholds?.battery;
       const batterySymbol = batteryThreshold !== undefined && status.batteryCapacity >= batteryThreshold
         ? symbols.success