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/run/event-state.ts

@@ -0,0 +1,25 @@
+export interface EventState {
+  mainSessionIdle: boolean
+  mainSessionError: boolean
+  lastError: string | null
+  lastOutput: string
+  lastPartText: string
+  currentTool: string | null
+  /** Set to true when the main session has produced meaningful work (text, tool call, or tool result) */
+  hasReceivedMeaningfulWork: boolean
+  /** Count of assistant messages for the main session */
+  messageCount: number
+}
+
+export function createEventState(): EventState {
+  return {
+    mainSessionIdle: false,
+    mainSessionError: false,
+    lastError: null,
+    lastOutput: "",
+    lastPartText: "",
+    currentTool: null,
+    hasReceivedMeaningfulWork: false,
+    messageCount: 0,
+  }
+}