fix: prevent custom endpoint labels from overflowing

[oz-for-oss]

Closes #12189

Summary

• Wrap custom endpoint model chips across lines in Settings instead of rendering them as one unbounded row.
• Truncate long custom endpoint names with an ellipsis in the endpoint list and removal confirmation dialog so user-provided labels do not crowd action buttons or overflow cards.

Validation

• ./script/format
• cargo test -p warp validate_url --lib
• cargo clippy -p warp --lib --tests --all-features -- -D warnings

Notes

• No approved spec context was attached for this issue.
• The required .agents/shared/scripts/fetch_github_context.py script was not present in this checkout, so issue body/comments were not fetched through any alternate path per the prompt's script-only rule.
• The full required cargo clippy --workspace --all-targets --all-features --tests -- -D warnings command was attempted but blocked by missing generated preview_config.json/stable_config.json files; ./script/install_channel_config could not install them because this cloud environment lacks access to the private warp-channel-config SSH repository.