[Backend] Add .dockerignore to server

[Yunusabdul38]

Description: Improve Docker build hygiene by excluding unnecessary files from the build context, reducing image size. Tasks:

Create server/.dockerignore.
Add target/, .env, and local git files to the ignore list.
Verify the build context size is reduced.

[Rajkoli145]

@Rajkoli145 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Hi @Agora-Events,
I’d like to work on this issue.

I’ll add a .dockerignore file for the backend to exclude unnecessary files and keep the Docker build clean and efficient.

Happy to align with any preferred exclusions if needed.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Rajkoli145 to this issue.

[SamixYasuke]

@SamixYasuke has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Hi maintainer, I have experience working with docker files, I'd like to handle this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @SamixYasuke to this issue.

[Chibey-max]

@Chibey-max has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

i would like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Chibey-max to this issue.

[drips-wave]

Congratulations, @Chibey-max! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @Chibey-max: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[drips-wave]

This issue has been completed by @Chibey-max as part of the Stellar Wave Program's 3rd Wave 🥳

😎 @Chibey-max: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.