Summary

Closes #1617

• Add new AddQuartz overloads accepting Action<IServiceCollectionQuartzConfigurator, IServiceProvider>, allowing users to resolve DI services during Quartz configuration (e.g. to obtain connection strings from a DatabaseConnectionFactory)
• The configuration delegate is deferred until IOptions<QuartzOptions>.Value is accessed, at which point IServiceProvider is available
• All configurator operations (properties, AddJob, AddTrigger, ScheduleJob, AddCalendar, listeners) work transparently in the deferred context via a DeferredServiceCollection wrapper
• Supports default schedulers, named schedulers, and NameValueCollection property overloads
• No breaking changes — only additive new overloads and internal plumbing

New API

// Resolve services during Quartz configuration
services.AddQuartz((q, sp) =>
{
    var dbFactory = sp.GetRequiredService<DatabaseConnectionFactory>();
    q.UsePersistentStore(s =>
    {
        s.UseSqlServer(sqlServer =>
        {
            sqlServer.ConnectionString = dbFactory.GetConnectionString();
        });
    });
});

// Also works with named schedulers
services.AddQuartz("MyScheduler", (q, sp) => { ... });

// And with initial properties
services.AddQuartz(properties, (q, sp) => { ... });

Implementation

• DeferredQuartzConfiguration — IConfigureNamedOptions<QuartzOptions> that defers the user's configure lambda
• DeferredServiceCollection — IServiceCollection wrapper that intercepts service registrations (jobs, triggers, listeners, calendars) and applies them directly to QuartzOptions
• ListenerCreationHelper — Shared static helper extracted from NamedSchedulerFactory for creating listener instances from configuration objects
• ServiceCollectionSchedulerFactory and NamedSchedulerFactory updated to process deferred listeners/calendars

Test plan

• 23 new tests covering:
  • Property configuration with IServiceProvider (scheduler name, connection strings, IOptions<T>)
  • AddJob/AddTrigger/ScheduleJob/AddCalendar in deferred lambda
  • Scheduler and job listener registration in deferred lambda
  • Named scheduler isolation with deferred config
  • Combined immediate + deferred configuration (accumulation and override)
  • Full scheduler creation integration tests (listeners wired, calendars added, jobs scheduled)
  • End-to-end API proof matching the original issue scenario
• All 1307 existing unit tests pass — no regressions

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