refactor: Extract ProfileWorker into modular components

- Create ProfileWorker namespace with 4 separate components
- ProfileWorker.cs: BackgroundService orchestrator with IOptions support
- ProfileWorkerOptions.cs: Configuration model with validation
- ProfileCache.cs: Thread-safe cache using composition pattern
- DependencyInjection.cs: Service registration with IValidateOptions

Benefits:
- Separation of concerns (orchestration, config, state, DI)
- IOptions pattern for appsettings.json configuration
- Startup validation for configuration errors
- Better testability and maintainability

ECMJobRunner.WebCron/ProfileWorker/ProfileCache.cs

@@ -0,0 +1,23 @@
+using ECMJobRunner.Application.Common.Dtos;
+using System.Collections.Concurrent;
+
+namespace ECMJobRunner.WebCron.ProfileWorker;
+
+/// <summary>
+/// Thread-safe cache for storing active profile configurations.
+/// Used to track profile state and detect changes in schedule or removal.
+/// </summary>
+public class ProfileCache
+{
+    private readonly ConcurrentDictionary<string, CfgProfileDto> _cache = new();
+
+    public CfgProfileDto? Get(string jobId) => _cache.TryGetValue(jobId, out var profile) ? profile : null;
+
+    public void AddOrUpdate(string jobId, CfgProfileDto profile) => _cache[jobId] = profile;
+
+    public bool TryRemove(string jobId, out CfgProfileDto? profile) => _cache.TryRemove(jobId, out profile);
+
+    public IEnumerable<string> GetAllJobIds() => _cache.Keys;
+
+    public bool TryGetValue(string jobId, out CfgProfileDto? profile) => _cache.TryGetValue(jobId, out profile);
+}