fix: support OpenCode startup with Databricks app SP OAuth

[dgokeeffe]

Problem

OpenCode proxy setup assumes DATABRICKS_TOKEN is present and the terminal prompts for a PAT even when CoDA has a working Databricks app service-principal OAuth profile. This prevents the required Omnigent-attached CoDA path from running without manual PAT injection.

Acceptance criteria

• Allow the content-filter proxy to obtain credentials through app SP OAuth.
• Select the omnigents-host profile for attached terminal sessions.
• Skip the PAT prompt when SP OAuth is valid.
• Retain PAT behavior as fallback.
• Verify Pi and OpenCode launch through Omnigent without manual PAT injection.