feat: add duplicate cron job functionality

[simon-suess]

What this changes

Duplicate cron jobs with d keybinding. Copies:

• Job ID with _copy suffix (e.g., backup_job → backup_job_copy)
• Schedule expression and command
• Log settings (enable/disable logging status)
• Works for local and remote SSH jobs

Updates:

• CronTable: action_duplicate_cronjob() method
• CronCreator: accepts optional log_enabled parameter
• app.py: passes duplicate_data dict to editor
• README: added feature to list + keyboard shortcuts table
• Extracted NO_ID_LABEL constant (DRY)

How I tested this

• All 108 unit tests pass
• Manual verification: feature works on my machine xD
• Added 4 binding/method tests in CronTable_duplicate_test.py

Checklist

• I have read CONTRIBUTING.md and this PR follows the guidelines
• A human has reviewed the entire diff of this PR, every line of code
• A human understands the changes and can explain why this approach is correct
• This PR doesn't have AI-generated boilerplate or co-author lines
• This PR was authored and submitted by an AI agent without human review

[antoniorodr]

Hello @simon-suess!

Thanks for this PR.

A question: In which scenarios will be this useful? I mean, why would someone want to duplicate a cronjob?

I am not saying this is not useful, I just want to understand the use case better.

Thanks!

[simon-suess]

Hello @antoniorodr,

 if you think that this feature is not needed or some people wouldn't or most people wouldn't use it, feel free to keep it out. I mainly did it for myself, but thought that contributing would be cool if other people needed it too.
 
 For me it felt natural to also have a duplicate feature and I just needed it. I use Cornboard on my Mac to do updates, do some networking stuff. And for example I duplicated my old cron job where everything is configured and just changed the script that is executed. So everything else is already configured, i just change the command. Another time i used it for example, I want to update my brew dependencies once at 8am in the morning. But if I am not yet logged or have my Mac open it wont do it, so i duplicated it and set the start time to 9am. So even if I start work a bit later, I still update brew.
 
 Hope that makes my use case clear. Thanks.

[antoniorodr]

@simon-suess

I will check the PR out. I understand the use case you are trying to address, and it does not seem like a bad idea to me. And it does not hurt to habe more options for users.

I am feeling under the weather tho, but I will try to review it as soon as I can. Thanks for your patience!

[antoniorodr]

Hello @simon-suess!

I have not forgotten about this PR, but I have been busy with other things. I will try to review it this week. Thanks for your patience!

[antoniorodr]

Hello @simon-suess!

I have not forgotten about this PR, but I have been busy with other things. I will try to review it this week. Thanks for your patience!

[antoniorodr]

I have added some comments to the PR. I have not checked all the files, because I prefer you to answer/fix this first.

Thanks for your patience!

[antoniorodr]

Suggested change

	.idea
	.idea

[antoniorodr]

What I meant was: why did you add this to the file?

[antoniorodr]

They shortcurs are covered on the website documentation. That's why I didn't choose to have it on the README.md.

[antoniorodr]

Why are you converting a bool to string? And why are you converting it this way?

[antoniorodr]

Here are you using self.log_enabled as a boolean, but on CronTable you are converting the value to a string.