Add unit tests for channel utilities and configure testing environment

- Created a new test file `channels.test.ts` to cover utilities related to channel configurations and targets.
- Implemented tests for normalizing and grouping selected channels by type, as well as building channel targets from account data and cron history.
- Mocked necessary dependencies to isolate tests and ensure accurate results.
- Updated `vite.config.ts` to set up the testing environment with jsdom and enable global variables for tests.

package.json

@@ -10,6 +10,7 @@
     "start": "vite",
     "build": "vite build && electron-builder",
     "build:vite": "vite build",
+    "test": "vitest run",
     "smoke:agents": "node scripts/agents-runtime-smoke.mjs",
     "package": "vite build",
     "icons": "zx scripts/generate-icons.mjs",