fix(expo): support anthropic_oauth_json auth type in provider form

The backend aiProviderProfiles authType union added 'anthropic_oauth_json'
but the Expo provider form's local AuthType type was stale, breaking
typecheck. Add the literal, a picker option, help text, and multiline
handling to match the Next app.

Claude-Session: https://claude.ai/code/session_01ScyZ1NhfN84LAnHpwhfEQk

apps/expo/src/components/settings/ai-provider-profile-form.tsx

@@ -20,7 +20,11 @@ type Provider =
   | 'cloudflare_ai_gateway'
   | 'custom_openai_compatible'
   | 'opencode_openai_login';
-type AuthType = 'api_key' | 'opencode_auth_json' | 'none';
+type AuthType =
+  | 'api_key'
+  | 'opencode_auth_json'
+  | 'anthropic_oauth_json'
+  | 'none';
 type ReasoningEffort = 'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh';
 
 type ExistingProfile = {
@@ -174,6 +178,7 @@ export const AiProviderProfileForm = ({
         options={[
           { label: 'API key', value: 'api_key' },
           { label: 'Codex auth JSON', value: 'opencode_auth_json' },
+          { label: 'Anthropic OAuth JSON', value: 'anthropic_oauth_json' },
           { label: 'None', value: 'none' },
         ]}
         value={authType}
@@ -186,10 +191,20 @@ export const AiProviderProfileForm = ({
           agent workspaces for Codex CLI runs.
         </Text>
       ) : null}
+      {authType === 'anthropic_oauth_json' ? (
+        <Text className='text-muted-foreground text-sm leading-5'>
+          Paste the credentials JSON from your Claude auth folder, for example
+          ~/.claude/.credentials.json, and paste it here. Spoon writes it into
+          isolated agent workspaces for Claude Code CLI runs.
+        </Text>
+      ) : null}
       {authType !== 'none' ? (
         <Field
           label={authType === 'api_key' ? 'API key' : 'Auth JSON'}
-          multiline={authType === 'opencode_auth_json'}
+          multiline={
+            authType === 'opencode_auth_json' ||
+            authType === 'anthropic_oauth_json'
+          }
           secureTextEntry={authType === 'api_key'}
           value={secret}
           onChangeText={setSecret}