fix(doctor): display user-configured variant in model resolution output

[edxeth]

Summary

• Fix doctor command showing incorrect/missing variants in model resolution output
• OmoConfig interface was missing variant property, causing doctor to display variants from ModelRequirement fallback chain instead of user's config

Changes

• Add variant to OmoConfig agent/category entries
• Add userVariant to AgentResolutionInfo and CategoryResolutionInfo
• Update getEffectiveVariant() to prioritize user variant over requirement defaults
• Add 2 tests verifying variant capture for agents and categories

Before/After

Agent	Config	Before	After
oracle	xhigh	high	xhigh ✓
metis	xhigh	max	xhigh ✓
momus	max	medium	max ✓
librarian	high	(missing)	high ✓
explore	high	(missing)	high ✓
multimodal-looker	high	(missing)	high ✓

---

Summary by cubic

Fixes the doctor command to show user-configured model variants in the model resolution output. Previously, variants came from the fallback chain, leading to wrong or missing values.

• Bug Fixes
  • Add variant to OmoConfig agent/category entries.
  • Capture userVariant in AgentResolutionInfo and CategoryResolutionInfo.
  • Prioritize user variant in getEffectiveVariant.
  • Add tests for agent and category variant capture.

^{Written for commit 7e00516. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.