feat(calendar): Add extensible Connect Calendar and Calendar Settings modals

[gloriafolaron]

Summary

• Adds extensible Connect Calendar modal for connecting external calendars
• Adds extensible Calendar Settings modal for managing calendar integrations
• Provides filter hooks for plugins to inject their own calendar providers and settings sections

Changes

New Controllers

• ConnectCalendar.php - Modal for connecting external calendars with filter connectOptions.providers
• CalendarSettings.php - Modal for calendar settings with filter calendarSettings.sections

New Templates

• connectCalendar.blade.php - Extensible modal with built-in iCal URL import
• calendarSettings.blade.php - Settings modal showing connected calendars and plugin sections

Plugin Integration

Plugins can register their calendar providers via filters:

// Add to Connect Calendar modal
EventDispatcher::add_filter_listener(
    'leantime.domain.calendar.controllers.connectcalendar.run.connectOptions.providers',
    function (array $providers) {
        $providers[] = [
            'id' => 'myplugin',
            'icon' => 'fa fa-calendar',
            'title' => 'My Calendar',
            'description' => 'Connect your calendar',
            'actionUrl' => '/myplugin/connect',
            'actionLabel' => 'Connect',
        ];
        return $providers;
    }
);

// Add to Calendar Settings modal
EventDispatcher::add_filter_listener(
    'leantime.domain.calendar.controllers.calendarsettings.get.calendarSettings.sections',
    function (array $sections) {
        $sections[] = [
            'id' => 'myplugin',
            'title' => 'My Calendar Settings',
            'content' => '<p>Settings content here</p>',
        ];
        return $sections;
    }
);

Related

• Google Calendar plugin PR: https://github.com/Leantime/plugins/pull/34

Test plan

• Click "Connect Calendar" in calendar sidebar - modal should open with iCal option
• With Google Calendar plugin enabled, modal should show Google Calendar option
• Calendar Settings modal shows connected external calendars
• Plugin sections appear in Calendar Settings when plugins are enabled

cc @marcelfolaron

🤖 Generated with Claude Code

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}