refactor(cli): split doctor/model-resolution and run/events into focused modules

Doctor checks:
- model-resolution-cache.ts, model-resolution-config.ts
- model-resolution-details.ts, model-resolution-effective-model.ts
- model-resolution-types.ts, model-resolution-variant.ts

Run events:
- event-formatting.ts, event-handlers.ts
- event-state.ts, event-stream-processor.ts

src/cli/doctor/checks/model-resolution-variant.ts

@@ -0,0 +1,55 @@
+import type { ModelRequirement } from "../../../shared/model-requirements"
+import type { OmoConfig } from "./model-resolution-types"
+
+export function formatModelWithVariant(model: string, variant?: string): string {
+  return variant ? `${model} (${variant})` : model
+}
+
+function getAgentOverride(
+  agentName: string,
+  config: OmoConfig
+): { variant?: string; category?: string } | undefined {
+  const agentOverrides = config.agents
+  if (!agentOverrides) return undefined
+
+  return (
+    agentOverrides[agentName] ??
+    Object.entries(agentOverrides).find(([key]) => key.toLowerCase() === agentName.toLowerCase())?.[1]
+  )
+}
+
+export function getEffectiveVariant(
+  agentName: string,
+  requirement: ModelRequirement,
+  config: OmoConfig
+): string | undefined {
+  const agentOverride = getAgentOverride(agentName, config)
+
+  if (agentOverride?.variant) {
+    return agentOverride.variant
+  }
+
+  const categoryName = agentOverride?.category
+  if (categoryName) {
+    const categoryVariant = config.categories?.[categoryName]?.variant
+    if (categoryVariant) {
+      return categoryVariant
+    }
+  }
+
+  const firstEntry = requirement.fallbackChain[0]
+  return firstEntry?.variant ?? requirement.variant
+}
+
+export function getCategoryEffectiveVariant(
+  categoryName: string,
+  requirement: ModelRequirement,
+  config: OmoConfig
+): string | undefined {
+  const categoryVariant = config.categories?.[categoryName]?.variant
+  if (categoryVariant) {
+    return categoryVariant
+  }
+  const firstEntry = requirement.fallbackChain[0]
+  return firstEntry?.variant ?? requirement.variant
+}