feat: SDS improvements

[weboko]

Description

During internal testing and wrapper development, several issues and inconsistencies were identified that reduce clarity, maintainability, and correctness of the implementation:

• Naming inconsistencies in events, methods, and variables caused confusion, especially when terms from the spec (e.g., “delivered”) could be misinterpreted.
• Verb choices in methods like sendMessage/receiveMessage were misleading, as they did not reflect the actual behavior (messages are queued for SDS rather than directly sent/received).
• The Message structure lacked convenient methods for encoding/decoding, complicating usage.
• acknowledgements terminology diverged from spec language (“possible” vs “partial”), creating semantic mismatches.
• Event emission logic sometimes triggered events even when the underlying action did not occur.
• Duplicate messages in history caused acknowledgment handling problems.
• Testing coverage and logging were insufficient for debugging and validation.

Proposed Solution / Feature Design

To increase wrapper maturity and align it more closely with the spec, the following improvements have been implemented or initiated:

1. Spec alignment – Added senderId per new spec PR #170.
2. Better data model – Converted Message to a class to provide built-in encode/decode methods for easier handling.
3. Clearer event naming – Adjusted event names to clearly indicate whether they relate to incoming or outgoing messages, avoiding spec term ambiguity.
4. Accurate method naming – Replaced misleading verbs (sendMessage, receiveMessage) with terminology that reflects actual SDS behavior.
5. Consistent terminology – Updated acknowledgements naming to match spec’s “possible” acknowledgment concept.
6. Improved logging and tests – Added/fixed tests and introduced logs for better traceability.
7. Event emission correctness – Ensured events are only emitted when the related action truly occurred (e.g., “delivered” only when delivery happens).
8. Duplicate message mitigation – Began removing history duplication to prevent acknowledgment issues (full fix planned in a separate PR).

[weboko]

resolved with #2539