v2.1.8

improvements

• fixed #272 malformed expand request in fetchCalendarObjects
• optimized fetchCalendarObjects to reduce redundant requests when expand is true
• added Bearer auth support for token-based providers (e.g., Nextcloud OIDC)
• added fetch overrides across account, request, and collection helpers for custom transports
• prefer native fetch in Cloudflare Workers to avoid cross-fetch incompatibilities
• collectionQuery now rejects on non-OK responses instead of returning empty arrays
• fetchVCards filters out collection URLs to avoid empty/invalid entries (Radicale-compatible)
• docs updates for iCal feed import, providers, and custom transport guidance