adka2a event processor logic (part 2) (#151)

Commit: 4b493e0

Date: October 20, 2025 at 7:51 AM

Event processing logic required for adka2a adapter.

For every `session.Event` produce a `TaskArtifactUpdateEvent{Append=true}` with transformed parts.
After the last `session.Event` is processed produce an empty `TaskArtifactUpdateEvent{Append=true}` with `LastChunk=true`, if at least one artifact update was produced during the run.
If there was an `LLMResponse` with non-zero error code, produce a `TaskStatusUpdateEvent` with `TaskStateFailed`.

Else if there was an `LLMResponse` with long-running tool invocation, produce a `TaskStatusUpdateEvent` with `TaskStateInputRequired`.

Else produce a `TaskStatusUpdateEvent` with `TaskStateCompleted`.

gitv1