feat(migrations): add migration system for v3→v4 config format

- Create abstract BaseMigration class with order, shouldRun(), migrate()
- Add MigrationRunner to execute migrations in order
- Add Migration v1→v2 (snmp → upsDevices)
- Add Migration v3→v4 (upsList → upsDevices)
- Update INupstConfig with version field
- Update loadConfig() to run migrations automatically
- Update saveConfig() to ensure version field and remove legacy fields
- Update Docker test scripts to use real UPS data from .nogit/env.json
- Remove colors.bright (not available in @std/fmt/colors)

Config migrations allow users to jump versions (e.g., v1→v4) with all
intermediate migrations running automatically. Version field tracks
config format for future migrations.

ts/migrations/base-migration.ts

@@ -0,0 +1,54 @@
+/**
+ * Abstract base class for configuration migrations
+ *
+ * Each migration represents an upgrade from one config version to another.
+ * Migrations run in order based on the `order` field, allowing users to jump
+ * multiple versions (e.g., v1 → v4 runs migrations 2, 3, and 4).
+ */
+export abstract class BaseMigration {
+  /**
+   * Migration order number
+   * - Order 2: v1 → v2
+   * - Order 3: v2 → v3
+   * - Order 4: v3 → v4
+   * etc.
+   */
+  abstract readonly order: number;
+
+  /**
+   * Source version this migration upgrades from
+   * e.g., "1.x", "3.x"
+   */
+  abstract readonly fromVersion: string;
+
+  /**
+   * Target version this migration upgrades to
+   * e.g., "2.0", "4.0"
+   */
+  abstract readonly toVersion: string;
+
+  /**
+   * Check if this migration should run on the given config
+   *
+   * @param config - Raw configuration object to check
+   * @returns True if migration should run, false otherwise
+   */
+  abstract shouldRun(config: any): Promise<boolean>;
+
+  /**
+   * Perform the migration on the given config
+   *
+   * @param config - Raw configuration object to migrate
+   * @returns Migrated configuration object
+   */
+  abstract migrate(config: any): Promise<any>;
+
+  /**
+   * Get human-readable name for this migration
+   *
+   * @returns Migration name
+   */
+  getName(): string {
+    return `Migration ${this.fromVersion} → ${this.toVersion}`;
+  }
+}

ts/migrations/index.ts

@@ -0,0 +1,10 @@
+/**
+ * Configuration migrations module
+ *
+ * Exports the migration system for upgrading configs between versions.
+ */
+
+export { BaseMigration } from './base-migration.ts';
+export { MigrationRunner } from './migration-runner.ts';
+export { MigrationV1ToV2 } from './migration-v1-to-v2.ts';
+export { MigrationV3ToV4 } from './migration-v3-to-v4.ts';

ts/migrations/migration-runner.ts

@@ -0,0 +1,69 @@
+import { BaseMigration } from './base-migration.ts';
+import { MigrationV1ToV2 } from './migration-v1-to-v2.ts';
+import { MigrationV3ToV4 } from './migration-v3-to-v4.ts';
+import { logger } from '../logger.ts';
+
+/**
+ * Migration runner
+ *
+ * Discovers all available migrations, sorts them by order,
+ * and runs applicable migrations in sequence.
+ */
+export class MigrationRunner {
+  private migrations: BaseMigration[];
+
+  constructor() {
+    // Register all migrations here
+    this.migrations = [
+      new MigrationV1ToV2(),
+      new MigrationV3ToV4(),
+      // Add future migrations here (v4→v5, v5→v6, etc.)
+    ];
+
+    // Sort by order to ensure they run in sequence
+    this.migrations.sort((a, b) => a.order - b.order);
+  }
+
+  /**
+   * Run all applicable migrations on the config
+   *
+   * @param config - Raw configuration object to migrate
+   * @returns Migrated configuration and whether migrations ran
+   */
+  async run(config: any): Promise<{ config: any; migrated: boolean }> {
+    let currentConfig = config;
+    let anyMigrationsRan = false;
+
+    logger.dim('Checking for required config migrations...');
+
+    for (const migration of this.migrations) {
+      const shouldRun = await migration.shouldRun(currentConfig);
+
+      if (shouldRun) {
+        logger.info(`Running ${migration.getName()}...`);
+        currentConfig = await migration.migrate(currentConfig);
+        anyMigrationsRan = true;
+      }
+    }
+
+    if (anyMigrationsRan) {
+      logger.success('Configuration migrations complete');
+    } else {
+      logger.dim('No migrations needed');
+    }
+
+    return {
+      config: currentConfig,
+      migrated: anyMigrationsRan,
+    };
+  }
+
+  /**
+   * Get all registered migrations
+   *
+   * @returns Array of all migrations sorted by order
+   */
+  getMigrations(): BaseMigration[] {
+    return [...this.migrations];
+  }
+}

ts/migrations/migration-v1-to-v2.ts

@@ -0,0 +1,56 @@
+import { BaseMigration } from './base-migration.ts';
+import { logger } from '../logger.ts';
+
+/**
+ * Migration from v1 (single SNMP config) to v2 (upsDevices array)
+ *
+ * Detects old format:
+ * {
+ *   snmp: { ... },
+ *   thresholds: { ... },
+ *   checkInterval: 30000
+ * }
+ *
+ * Converts to:
+ * {
+ *   version: "2.0",
+ *   upsDevices: [{ id: "default", name: "Default UPS", snmp: ..., thresholds: ... }],
+ *   groups: [],
+ *   checkInterval: 30000
+ * }
+ */
+export class MigrationV1ToV2 extends BaseMigration {
+  readonly order = 2;
+  readonly fromVersion = '1.x';
+  readonly toVersion = '2.0';
+
+  async shouldRun(config: any): Promise<boolean> {
+    // V1 format has snmp field directly at root, no upsDevices or upsList
+    return !!config.snmp && !config.upsDevices && !config.upsList;
+  }
+
+  async migrate(config: any): Promise<any> {
+    logger.info(`${this.getName()}: Converting single SNMP config to multi-UPS format...`);
+
+    const migrated = {
+      version: this.toVersion,
+      upsDevices: [
+        {
+          id: 'default',
+          name: 'Default UPS',
+          snmp: config.snmp,
+          thresholds: config.thresholds || {
+            battery: 60,
+            runtime: 20,
+          },
+          groups: [],
+        },
+      ],
+      groups: [],
+      checkInterval: config.checkInterval || 30000,
+    };
+
+    logger.success(`${this.getName()}: Migration complete`);
+    return migrated;
+  }
+}

ts/migrations/migration-v3-to-v4.ts

@@ -0,0 +1,45 @@
+import { BaseMigration } from './base-migration.ts';
+import { logger } from '../logger.ts';
+
+/**
+ * Migration from v3 (upsList) to v4 (upsDevices)
+ *
+ * Detects v3 format:
+ * {
+ *   upsList: [ ... ],
+ *   groups: [ ... ],
+ *   checkInterval: 30000
+ * }
+ *
+ * Converts to:
+ * {
+ *   version: "4.0",
+ *   upsDevices: [ ... ],  // renamed from upsList
+ *   groups: [ ... ],
+ *   checkInterval: 30000
+ * }
+ */
+export class MigrationV3ToV4 extends BaseMigration {
+  readonly order = 4;
+  readonly fromVersion = '3.x';
+  readonly toVersion = '4.0';
+
+  async shouldRun(config: any): Promise<boolean> {
+    // V3 format has upsList instead of upsDevices
+    return !!config.upsList && !config.upsDevices;
+  }
+
+  async migrate(config: any): Promise<any> {
+    logger.info(`${this.getName()}: Renaming upsList to upsDevices...`);
+
+    const migrated = {
+      version: this.toVersion,
+      upsDevices: config.upsList,  // Rename upsList → upsDevices
+      groups: config.groups || [],
+      checkInterval: config.checkInterval || 30000,
+    };
+
+    logger.success(`${this.getName()}: Migration complete`);
+    return migrated;
+  }
+}