feat: support session-scoped model overrides

Model selection was acting like a provider-level preference.

That made resumed sessions drift back to a default or request-time model.

Users expect /models changes made inside a conversation to affect that session.

Store explicit session choices in app-owned ~/.cloudcli state.

This avoids editing provider transcripts or native provider config.

Resolve the effective model before launching each provider runtime.

Claude, Cursor, Codex, Gemini, and OpenCode now honor stored resume choices.

Expose a backend active-model change endpoint for existing sessions.

The models modal can now distinguish default changes from session overrides.

It also shows when a selected model will apply on the next response.

For Claude, stop probing active model state by resuming with a dummy prompt.

Read the indexed JSONL transcript from the end instead.

This preserves provider history while honoring /model stdout or model fields.

Add service tests for adapter delegation and resume-model precedence.

The tests keep cache state, override state, and requested fallback separate.

server/modules/providers/list/cursor/cursor-models.provider.ts

@@ -7,13 +7,16 @@ import crossSpawn from 'cross-spawn';
 
 import type { IProviderModels } from '@/shared/interfaces.js';
 import type {
+  ProviderChangeActiveModelInput,
   ProviderCurrentActiveModel,
   ProviderModelOption,
   ProviderModelsDefinition,
+  ProviderSessionActiveModelChange,
 } from '@/shared/types.js';
 import {
   buildDefaultProviderCurrentActiveModel,
   sanitizeLeafDirectoryName,
+  writeProviderSessionActiveModelChange,
 } from '@/shared/utils.js';
 
 export const CURSOR_FALLBACK_MODELS: ProviderModelsDefinition = {
@@ -257,4 +260,10 @@ export class CursorProviderModels implements IProviderModels {
 
     return buildDefaultProviderCurrentActiveModel(await this.getSupportedModels());
   }
+
+  async changeActiveModel(
+    input: ProviderChangeActiveModelInput,
+  ): Promise<ProviderSessionActiveModelChange> {
+    return writeProviderSessionActiveModelChange('cursor', input);
+  }
 }