Enable stricter dynamic-related analysis

[parlough]

Enables and fixes the resulting diagnostics from:

• strict-raw-types
• avoid_annotating_with_dynamic
• strict_top_level_inference

[gemini-code-assist]

Code Review

This pull request enables stricter static analysis for dynamic types, which is a great improvement for the overall code health and maintainability. The changes across the codebase correctly address the new lint rules by providing explicit type arguments and avoiding dynamic. I found one minor issue where an incorrect type argument was used, and I've left a suggestion to fix it. Otherwise, the changes look solid. Well done!

[gemini-code-assist]

The type argument for StreamSubscription should be String to match the stream it's subscribing to. The surfaceUpdateController.stream is a Stream<String>, so the subscription should be of type StreamSubscription<String>? to correctly reflect the type of data flowing through the stream.

Suggested change

	StreamSubscription<void>? _subscription;
	StreamSubscription<String>? _subscription;

[parlough]

In this case, we explicitly don't care about the data flowing through the stream. We only use the subscription for cancellation, so void helps indicate we shouldn't/don't want to access the data through it.