feat. add crontab explainer

[madhav2348]

Description

Implementing crontab explainer, while project already have crontab generator, this will provides a clear, human-readable sentence explaining the schedule (leveraging and extending the existing
humanize logic).

Fixes #32

Dependencies

NA

Future Improvements

NA

Mentions

@rishima17

Screenshots of relevant screens

Developer's checklist

• My PR follows the style guidelines of this project
• I have performed a self-check on my work

If changes are made in the code:

• I have followed the Coding Guidelines
• My changes in code generate no new warnings
• My changes are not breaking another fix/feature of the project
• I have added test cases to show that my feature works
• I have added relevant screenshots in my PR
• There are no UI/UX issues

[SyedFahad7]

Thanks for the contribution @madhav2348 . I really like the direction here. The Crontab Explainer is a useful addition and it complements the existing generator nicely. I’ve reviewed this as production level logic though, and I can’t approve it in its current state because there are correctness issues that could mislead users.

Here are the key points that need to be addressed:

1. Day of Month and Day of Week logic mismatch
   I noticed the explanation text treats day of month and day of week as OR when both are set, but the execution preview logic appears to use strict AND. That means the explanation and the calculated next run times can disagree. This is a critical correctness issue.

2. Next 5 executions preview is incomplete
   The search window is capped at around 10,000 minutes, which is roughly 7 days. That means monthly or yearly schedules may not reliably show 5 executions. The preview needs to work for all valid cron expressions, not just short interval ones.

3. Validation is too weak
   Right now the validation only checks that there are 5 fields. Invalid values, ranges, and malformed expressions can still pass as valid. We need stronger validation before calling an expression valid.

4. Step parsing is incorrect for some patterns
   Expressions like 1-10/2 are not handled correctly because the step logic assumes a numeric base. This can lead to incorrect schedule interpretation.

5. UTC vs Local preview requirement
   The issue mentioned preview based on UTC or Local context, but the implementation currently only renders local time using toLocaleString(). That requirement is only partially fulfilled.

6. UX issue with preview toggle
   If no executions are found, the preview section does not render at all, which hides the toggle. That creates a confusing user experience.

7. Logic duplication
   This seems to duplicate cron explanation logic instead of reusing or extending the existing humanize path from the generator. We should align with the project’s reuse pattern for maintainability.

The overall idea is good and the routing and metadata wiring look correct. But since this tool deals with schedule correctness, it needs to be reliable before merging.

Please address the above points and open a fresh PR once updated. I’ll review it again quickly once the fixes are in.

[madhav2348]

Sure , some valid points you have share ,
Thanks for the review,I'll update as suggested as soon as possible