fix(tasks): resolve type errors

[google-labs-jules[bot]]

This pull request resolves all TypeScript type errors in the tasks directory by updating the code to modern Apps Script standards and adding comprehensive JSDoc annotations. The changes adhere to the guidelines in GEMINI.md and do not alter the core logic of the samples. All feedback from code reviews has been addressed.

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PR created automatically by Jules for task 7712502493904321920 started by @jpoehnelt

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