Introduced PostBuildBehavior enum and BehaveOnPostBuild() method to configure behavior when modifying the service collection after the service provider is built.
Replaced EnsureNotBuilt() with EnsureBuilt() to support configurable handling (throw exception or ignore).
This improves flexibility in scenarios where post-build service modifications should be optionally allowed or silently ignored.
Added an `IsBuilt` property and `EnsureNotBuilt()` helper to `Factory` class
to restrict modifications to the service collection once the service provider
has been built. This ensures immutability and prevents runtime inconsistencies
after initialization.
- Introduced Factory class in DigitalData.Core.Abstractions namespace
- Implements both IServiceProvider and IServiceCollection interfaces
- Provides singleton instance via static readonly Instance property
- Supports lazy initialization of IServiceProvider using Lazy<T>
- Includes full collection management (Add, Remove, Clear, etc.)
- Ensures compatibility with both .NET and .NET Framework via conditional directives
