feat(todo_plus): add Todoist filter support with project names and date colors

[beriba]

Adds support for displaying Todoist tasks by filter ID (from /app/filter/-). The filter's name is shown as the project header, and each task is prefixed with #ProjectName in yellow. Currently, only tasks for projects can be shown.
Changes:

• Todoist backend: fetch filters via Sync API and tasks via /api/v1/tasks/filter endpoint. Each task is enriched with its project name, parsed due date (supports ISO datetime with/without timezone), and overdue status.
• Task display: project name prefix in yellow, due date/time appended — shown in red when overdue. Tasks with dates sort chronologically first.
• Settings: support filters list in config (e.g. filters: ["1234567"]).