Milestone 2 — Task Repository

Implement the in-memory task store behind its interface — ID allocation included: ``csharp public sealed class TaskRepo : Solution.ITaskRepo { public TaskRepo(); // empty store public int NextId(); // starts at 1, monotonic public TaskItem Add(int projectId, string title, Priority priority); // allocates id, Todo, unassigned public bool TryFind(int id, out TaskItem task); public bool Update(TaskItem task); // replace by id; false when missing public System.Collections.Generic.IReadOnlyList<TaskItem> All(); } public interface ITaskRepo { int NextId(); TaskItem Add(int projectId, string title, Priority priority); bool TryFind(int id, out TaskItem task); bool Update(TaskItem task); System.Collections.Generic.IReadOnlyList<TaskItem> All(); } ` Both types nest inside Solution. Rules: - IDs start at 1 and increase by one per Add, independent of removal attempts (there are none — this repo never deletes), - Add stores the item as given (validation already happened at the service), - Update replaces the whole item; unknown ids return false and change nothing, - All` returns a snapshot safe to enumerate while the repo keeps changing (copy, not live view).