Add comprehensive iCal properties support to event creation modal

Enhanced the create event modal to include all major iCalendar properties:
- Event status (confirmed/tentative/cancelled)
- Privacy classification (public/private/confidential)
- Priority levels (0-9 numeric scale)
- Organizer email field
- Attendees list (comma-separated emails)
- Categories (comma-separated tags)
- Reminder options (none to 1 week before)
- Recurrence patterns (none/daily/weekly/monthly/yearly)

Updated backend to parse and handle all new fields, with proper enum conversion
and comma-separated list parsing. Events now generate complete iCal data with
STATUS, CLASS, PRIORITY, ORGANIZER, ATTENDEE, CATEGORIES, VALARM, and RRULE properties.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Cargo.toml

@@ -7,7 +7,24 @@ edition = "2021"
 
 [dependencies]
 yew = { version = "0.21", features = ["csr"] }
-web-sys = "0.3"
+web-sys = { version = "0.3", features = [
+    "console",
+    "HtmlSelectElement", 
+    "HtmlInputElement",
+    "HtmlTextAreaElement",
+    "Event",
+    "MouseEvent",
+    "InputEvent",
+    "Element",
+    "Document",
+    "Window",
+    "Location",
+    "Headers",
+    "Request",
+    "RequestInit",
+    "RequestMode",
+    "Response",
+] }
 wasm-bindgen = "0.2"
 
 # HTTP client for CalDAV requests