[Enhancement] Add Nvidia NIM embedding support (openai-compatible)

[Mirrowel]

Short description

Nvidia Nim embedding is openai-compatible, just needs additional fields.

What happened?

Diagnostics

Plugin version

0.21.18

OpenCode version

No response

Platform

No response

Client

OpenCode TUI (CLI)

Log output (optional)

[alfonso-magic-context]

Added in the upcoming release. New optional embedding.input_type and embedding.truncate config fields — set input_type: "query" (or "passage") for NVIDIA NIM. They're threaded through the live request, the provider identity (input_type changes the vector space, so changing it re-embeds), the endpoint probe, and the dashboard Test Connection. Omitted entirely when unset, so standard OpenAI endpoints are unaffected. Thanks for the clear report.