[FEATURE]: support named agent colors for CC compatibility (red, blue...)

[sentisso]

Feature hasn't been suggested before.

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Describe the enhancement you want to request

The color option for Claude Code subagents supports only named colors like: red, blue, green, yellow, purple, orange, pink, or cyan (see Claude Code docs).

This causes incompatiblity between Claude Code subagents and OpenCode subagents, for example this agent:

---
name: judge
description: Use this agent when evaluating implementation artifacts against an evaluation specification produced by the meta judge. Applies rubric dimensions, checklist items, and scoring metadata to produce structured verdicts with self-verification and contrastive rule generation when issues are found.
model: opus
color: red
---

causes opencode not to start:

$ opencode
Configuration is invalid at ~/.opencode/agents/judge.md
↳ Invalid string: must match pattern /^#[0-9a-fA-F]{6}$/ color

OpenCode should also support this color config.

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Invalid string: must match pattern /^#[0-9a-fA-F]{6}$/ color #23895: Same error message (Invalid string: must match pattern /^#[0-9a-fA-F]{6}$/ color) reported when using named colors (e.g. from Claude Code agents) in the agent config — same root cause, filed as a bug.
• [FEATURE]: allow using theme colors along with hex values in Agent's color config #11440 (closed): Related feature request to allow non-hex values in the agent color config field.