fix: resolve TypeScript errors in config set and model-defaults

- config/set.ts: move hyphen alias resolution after null check,
  type resolvedKey as string explicitly
- model-defaults.ts: use Config camelCase keys instead of
  ConfigFile snake_case keys

Author: raylanlin

src/commands/config/set.ts

@@ -33,9 +33,6 @@ export default defineCommand({
     const key = flags.key as string | undefined;
     const value = flags.value as string | undefined;
 
-    // Resolve hyphen aliases to underscore keys
-    const resolvedKey = KEY_ALIASES[key] || key;
-
     if (!key || value === undefined) {
       throw new CLIError(
         '--key and --value are required.',
@@ -44,6 +41,9 @@ export default defineCommand({
       );
     }
 
+    // Resolve hyphen aliases to underscore keys
+    const resolvedKey: string = KEY_ALIASES[key] || key;
+
     if (!VALID_KEYS.includes(resolvedKey)) {
       throw new CLIError(
         `Invalid config key "${key}". Valid keys: ${VALID_KEYS.join(', ')}`,

src/utils/model-defaults.ts

@@ -1,11 +1,11 @@
-import type { Config, ConfigFile } from '../config/schema';
+import type { Config } from '../config/schema';
 
 /**
  * Resolve the model for a given modality.
- * Priority: --model flag > config file default > hardcoded fallback.
+ * Priority: --model flag > config default > hardcoded fallback.
  */
 export function resolveModel(
-  modality: keyof Pick<ConfigFile, 'default_text_model' | 'default_speech_model' | 'default_video_model' | 'default_music_model'>,
+  defaultKey: 'defaultTextModel' | 'defaultSpeechModel' | 'defaultVideoModel' | 'defaultMusicModel',
   fallback: string,
   config: Config,
   flags: Record<string, unknown>,
@@ -14,8 +14,8 @@ export function resolveModel(
   if (typeof flags.model === 'string' && flags.model.length > 0) {
     return flags.model;
   }
-  // 2. Config file default
-  const configDefault = config[modality] as string | undefined;
+  // 2. Config default (runtime, camelCase)
+  const configDefault = config[defaultKey] as string | undefined;
   if (configDefault) return configDefault;
   // 3. Hardcoded fallback
   return fallback;