fix: resolve implicit global variables in github-queries.js

[praaatap]

Description

This PR fixes a few places where variables were being assigned without an explicit declaration (let, const, or var) in [js/github-queries.js]

• Pollution of the global namespace.
• Conflict with other scripts.
• Difficult-to-debug side effects.

I have refactored these places to use const because these variables are not being reassigned in their scopes.

Changes

• Declared date inside the function.
• Declared [tag]
• Declared count inside the stargazers-fetching closure.

Verification

• Verified by reviewing the script logic.
• Verified locally to ensure GitHub stats are still being fetched and displayed correctly.

[precice-bot]

This pull request has been mentioned on preCICE Forum on Discourse. There might be relevant details there:

https://precice.discourse.group/t/gsoc-2026-introduction-hanzalah-waheed/2745/5

[MakisH]

This makes sense overall.

@praaatap could you please update and resolve the conflicts? There is also an unresolved conversation.

[MakisH]

@praaatap the conflict resolution reverted the changes of #793.