Add dark mode for better eye comfort

[Bilalkamal]

• Implemented dark mode color scheme
• Added dark mode toggle functionality
• Improves accessibility and reduces eye strain

[cyclotruc]

@Bilalkamal Hi and thank you for this PR

It is something I wanted to do for a while and I simply lacked the time so your work is very valuable

That being said, there's a few things to consider before merging this:

• First, there has been many refactors and the merge looks pretty tricky

• While this is a good start, the general looks of the darkmode should be polished a bit before pushed to production
  Here's an example of a design I had in mind
  

• There's a little fade-in animation when switching mode (on the github icon and some of the footer text) I don't know if it's intentional but I think it's a bit distracting

Let me know if you want to keep working on this PR or if I should take it from here, anyway thank you very much

[Bilalkamal]

Hey @cyclotruc!
Thanks for the feedback! I'll simplify the changes to make merging easier. Regarding the design - while the blue looks great, a darker shade would be gentler on the eyes when viewing larger result boxes. Would you be open to exploring a darker shade?
I love using Gitingest and dark mode felt like a natural addition. Happy to continue refining the PR, though!

Keep up the good work!

[cyclotruc]

@Bilalkamal You're right it should probably be a darker shade for the main menu element since the goal is to reduce eye strain

You are very welcome to keep working on this PR if you'd like
Or start a new one to avoid the current merge conflicts

Feel free to pick colors that seem fitting to you we can always adjust later
And you can also give me access to your branch so I can help you

Thank you again!