Fix Todoist apps for API v1

[tlambrou]

Closes #3266

Summary

• migrate Todoist and Todoist Tasks from retired REST v2 calls to /api/v1/tasks/filter with query, limit=200, and cursor-aware response parsing
• update Todoist authorization and token endpoints while preserving both apps’ encrypted legacy OAuth credentials and existing configuration scope
• version and hash cache keys, fix empty/hidden-empty/unauthenticated/API-error rendering, and keep the list app to one priority-sorted API page
• regenerate both preview GIFs using synthetic content only

Validation

• pixlet check apps/todoist apps/todoisttasks
• synthetic Pixlet renders for zero, one, many, 200+, hidden-empty, unauthenticated, API-error, priority, and 500-character long-text states
• git diff --check

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Manual Review Required

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	Test	Details
🟡	App Dir	Touches files in multiple directories
🟡	Modules	Multiple .star files: apps/todoist/todoist.star, apps/todoisttasks/todoisttasks.star
🟡	Original Author	The original author (zephyern) does not match the PR author (tlambrou)

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[tlambrou]

I have read the CLA Document and I hereby sign the CLA