feat: align project discovery with opencode-antigravity-auth reference

- Store project IDs in composite refresh token format (refreshToken|projectId|managedProjectId)
- Add parseRefreshParts() and formatRefreshParts() for token handling
- Extract and persist subscription tier during project discovery
- Fetch subscription in blocking mode when missing from cached accounts
- Fix conditional duetProject setting to match reference implementation
- Export parseTierId() for reuse across modules

Co-Authored-By: Claude <noreply@anthropic.com>

src/cloudcode/model-api.js

@@ -128,7 +128,7 @@ export async function getModelQuotas(token, projectId = null) {
  * @param {string} tierId - The tier ID from the API
  * @returns {'free' | 'pro' | 'ultra' | 'unknown'} The subscription tier
  */
-function parseTierId(tierId) {
+export function parseTierId(tierId) {
     if (!tierId) return 'unknown';
     const lower = tierId.toLowerCase();