ICSParser.parse() silently drops EXDATE (exclusion dates)

[thedhanawada]

Bug Description

ICSParser defines EXDATE: 'excludeDates' in its propertyMap (line 26 in core/ics/ICSParser.js), but the parseProperty() switch statement (lines 223-288) has no case 'EXDATE' handler. This means exclusion dates in imported ICS files are silently dropped.

Impact

• Recurring events imported via ICS will not respect EXDATE rules
• Cancelled individual occurrences of recurring series will appear as normal events
• Data loss on ICS round-trip (import → export)

Expected Fix

Add an EXDATE case handler in parseProperty() that:

1. Parses comma-separated date values
2. Stores them in the event's excludeDates array
3. Handles both DATE and DATE-TIME formats per RFC 5545

Files

• core/ics/ICSParser.js:26 (propertyMap entry exists)
• core/ics/ICSParser.js:223-288 (missing case handler)