Add KubeCon NA 2025 talks

[RainbowMango]

This issue is used to track the talks video that happened at KubeCon NA 2025.

• Maximizing Global Potential: Cost-Optimized, High-Availability Workloads Across Regions
  • https://www.youtube.com/watch?v=VrXt_T8DkIo

[seanlaii]

We also have this talk at KubeCon NA 2025:

• Karmada in Action: Scaling AI Workloads Across Multi-Cluster at Scale: https://www.youtube.com/watch?v=M1-yTjC2hTI&t=1s

[zhzhuang-zju]

Here is the related talk I found, ignore if I am wrong

KubeCon NA 2024: Bloomberg's Journey to Manage a Multi-Cluster Training Application with Karmada https://www.youtube.com/watch?v=PmaiEKpM1-Q

Bloomberg’s Journey to Improve Resource Utilization in a Multi-Cluster Platform https://www.youtube.com/watch?v=lMtCSaHI9Uk

Kubecon China 2025: How Bloomberg Creates a Resilient Data Analytics Platform Using Karmada https://www.youtube.com/watch?v=oQMJj5Mf7QA

[RainbowMango]

Actually, we missed a lot. I think the source of truth is https://github.com/karmada-io/community/tree/main/talks and opened https://github.com/karmada-io/community/pull/166.

PS: We need another PR to update the README in the karmada repo, by adding a reference to there.