Add Stellar Developer Meeting notes for 02.07.2026 & 25.06.2026

[kaankacar]

This issue tracks adding the corresponding .mdx files to the relevant directory.

Meeting to Add:

2026-25-06: Gaian(https://www.youtube.com/watch?v=xqBgocb6bCM)
2026-02-07: Zarf(https://www.youtube.com/watch?v=N7PtAJaELzA)