refactor: improve config consistency and token limits

- Remove legacy childKey field from settingsSchema

- Add contextWindowSize and maxOutputTokens to documentation

- Refactor ContextUsageDisplay to accept contextWindowSize directly instead of Config object

- Add useMemo optimization for contextWindowSize in Footer component

- Fix logic gaps in contentGenerator for contextWindowSize and maxOutputTokens initialization

- Increase DEFAULT_OUTPUT_TOKEN_LIMIT from 4K to 8K for better usability

- Add fallback to default values when model is not available

packages/cli/src/ui/components/ContextUsageDisplay.tsx

@@ -6,26 +6,22 @@
 
 import { Text } from 'ink';
 import { theme } from '../semantic-colors.js';
-import { DEFAULT_TOKEN_LIMIT, type Config } from '@qwen-code/qwen-code-core';
+import { DEFAULT_TOKEN_LIMIT } from '@qwen-code/qwen-code-core';
 
 export const ContextUsageDisplay = ({
   promptTokenCount,
-  model: _model,
   terminalWidth,
-  config,
+  contextWindowSize,
 }: {
   promptTokenCount: number;
-  model: string;
   terminalWidth: number;
-  config: Config;
+  contextWindowSize?: number;
 }) => {
   if (promptTokenCount === 0) {
     return null;
   }
 
-  const contextLimit =
-    config.getContentGeneratorConfig()?.contextWindowSize ??
-    DEFAULT_TOKEN_LIMIT;
+  const contextLimit = contextWindowSize ?? DEFAULT_TOKEN_LIMIT;
   const percentage = promptTokenCount / contextLimit;
   const percentageUsed = (percentage * 100).toFixed(1);