Unit tests for JavaScript Data Models #365

Part of #357

Add unit test coverage for domain data models and query logic.

Target Modules

• models/task.js: Comma-separated assignee parsing/formatting, task state updates, filter logic, query builders
• models/timesheet.js: Duration arithmetic, quadrant calculations, date range filtering, timesheet aggregations
• models/project.js: Local ID to Odoo ID resolution, project hierarchy handling
• models/activity.js: Activity state checks, activity validation, activity list filters
• models/accounts.js: Default account resolution, active account checks, account validation
• models/notifications.js: Notification payload formatting, unread counts, type filters
• models/Main.js: Quadrant calculation helpers, analytics aggregation logic

Implementation

• Can be tested via Qt Quick Test (TestCase importing .js files via .import) or a headless test harness with mock SQLite data fixtures.