Adds GSoC proposal of Hardik (#467)

Author: Nik-09

Google-Summer-of-Code-2025.md

@@ -48,7 +48,7 @@ You might also enjoy the "weekly journals" from some of our previous contributor
 The following projects (with linked proposals) are selected as part of GSoC 2025:
 
 * [Mohit Ruwatia](pdfs/GSoC2025MohitRuwatia.pdf): Clean up the structure for study guides and worked examples. Mentor: Kevin Thomas. [Journal link](https://medium.com/@mohitruwatia2312)
-* Hardik Goyal (TODO: PDF will be added soon): Lesson player redesign. Mentor: Amy Yeung. [Journal link](https://medium.com/@hardikgoyal2003)
+* [Hardik Goyal](pdfs/GSoC2025HardikGoyal.pdf): Lesson player redesign. Mentor: Amy Yeung. [Journal link](https://medium.com/@hardikgoyal2003)
 * [Jayam Patel](pdfs/GSoC2025JayamPatel.pdf): Acceptance tests. Mentor: Christie Ho. [Journal link](https://garden.jayampatel.space/projects/acceptance-tests-gsoc-2025/)
 * [Manas Gupta](pdfs/GSoC2025ManasGupta.pdf): Android lint infrastructure and fixes. Mentor: Bhavuk Jain. [Journal link](https://medium.com/@manasgupta733/list/gsoc-2025-oppia-journal-9ecd5faf335c)
 * [Ayush Yadav](pdfs/GSoC2025AyushYadav.pdf): Platform Parameter Dashboard.  Mentor: Rama Devi. [Journal link](https://medium.com/@theayushyadav11)