fix(nvidia): remove retired Nemotron 3 Super from model picker

[nv-kasikritc]

Summary

• Remove the retiring Nemotron 3 Super ID from the NVIDIA curated picker while keeping Nemotron 3.5 Super VL first.
• Correct NVIDIA provider docs: Super VL accepts text, image, and video input.
• Add a regression assertion for the curated list.
• Leave OpenRouter snapshot entries untouched; this change targets the NVIDIA-hosted API.

Verification

• Parsed the static picker list and confirmed Super VL is first and the old NVIDIA ID is absent.
• git diff --check passes.
• Full pytest suite not run in the sparse worktree; CI should validate.

NVIDIA confirmed the old hosted endpoint will be replaced at the 2026-10-15 launch. Keep this PR in draft until then.