Windows support: cross-platform calendar integration

[mrf]

Summary

Add Windows support, primarily by implementing a cross-platform calendar integration to replace the macOS-only AppleScript approach.

Current State

• Calendar integration uses osascript to query Calendar.app (macOS only)
• Other panels (PRs, ports, git) should mostly work cross-platform already

Proposed Implementation

Calendar Options for Windows

1. Microsoft Graph API - Access Outlook/M365 calendars via REST API

   • Requires OAuth setup
   • Works for corporate M365 users

2. Google Calendar API - For users with Google calendars

   • OAuth flow required
   • Good coverage for personal/workspace users

3. ICS file parsing - Parse exported .ics files

   • No auth needed
   • User manually exports/syncs calendar
   • Could watch a file for changes

4. CalDAV protocol - Standard calendar protocol

   • Works with many providers (Google, iCloud, Fastmail, etc.)
   • More complex to implement

Recommended Approach

Start with a pluggable calendar backend:

trait CalendarProvider {
    fn get_events(&self, hours_ahead: u32) -> Result<Vec<Event>>;
}

// Implementations
struct MacOSCalendar;      // existing osascript
struct MicrosoftGraph;     // Windows/M365
struct GoogleCalendar;     // Cross-platform
struct IcsFileCalendar;    // Cross-platform, no auth

Configuration

[meetings]
enabled = true
provider = "auto"  # auto-detect, or: "macos", "msgraph", "google", "ics"
hours_ahead = 8

# For ICS provider
ics_path = "~/calendar.ics"

# For MS Graph (tokens stored in keyring)
msgraph_client_id = "..."

Other Cross-Platform Considerations

Component	macOS	Windows	Notes
Calendar	osascript	Needs impl	Main blocker
Ports	lsof	netstat	Minor changes
Git	git CLI	git CLI	Should work
PRs	gh CLI	gh CLI	Should work

Acceptance Criteria

• Calendar panel works on Windows with at least one provider
• Graceful fallback when calendar unavailable
• Document setup steps for each provider
• CI builds for Windows