Add GSoC 2025 Proposal:(Related to issue #619)_ Application_RabbiyaRiaz_API_Explorer

[rabbiyariaz]

PR Description

Added my GSoC 2025 proposal: "API Explorer for APIDash", located at
'doc/proposals/2025/gsoc/application_RabbiyaRiaz_API_Explorer.md'.

The proposal outlines my plan, timeline, and goals for building an intuitive API Explorer for APIDash.

Looking forward to feedback from the mentors. Thank you!

Related Issues

• Closes #

Checklist

• I have gone through the contributing guide
• I have updated my branch and synced it with project main branch before making this PR
• I am using the latest Flutter stable branch (run flutter upgrade and verify)
• I have run the tests (flutter test) and all tests are passing

Added/updated tests?

We encourage you to add relevant test cases.

• Yes
• No, and this is why: please replace this line with details on why tests have not been included

OS on which you have developed and tested the feature?

• Windows
• macOS
• Linux

[animator]

@rabbiyariaz Please go ahead and submit your proposal in GSoC website.