fix(data): preserve unknown activity side values

[aproskill81]

Summary

Preserve unknown Activity.side values instead of dropping them during Data API deserialization.

Problem

Activity.side is deserialized through a custom helper that currently maps:

• BUY -> Some(Side::Buy)
• SELL -> Some(Side::Sell)
• empty string -> None
• anything else -> None

This loses information for forward-compatibility cases, even though Side already supports Unknown(String).

As a result, if the API introduces a new non-empty side value, the SDK silently drops it instead of preserving the raw value.

Fix

Update deserialize_optional_side so that:

• BUY deserializes to Some(Side::Buy)
• SELL deserializes to Some(Side::Sell)
• empty string still deserializes to None
• any other non-empty value deserializes to Some(Side::Unknown(raw))

Tests

Added coverage for:

• preserving an unknown side value
• keeping empty string behavior as None

---

Note

Low Risk
Low risk: small, localized change to Activity.side deserialization plus tests; behavior only differs for previously-unrecognized non-empty side values.

Overview
Updates Data API Activity.side deserialization to preserve any non-empty, unrecognized side string as Some(Side::Unknown(raw)) rather than coercing it to None (while keeping empty strings as None).

Adds test coverage to ensure unknown side values round-trip into Side::Unknown and that empty side strings continue to deserialize to None.

^{Written by Cursor Bugbot for commit 938b4ba. This will update automatically on new commits. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.58%. Comparing base (da07892) to head (938b4ba).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #305      +/-   ##
==========================================
+ Coverage   85.54%   85.58%   +0.04%     
==========================================
  Files          32       32              
  Lines        5167     5169       +2     
==========================================
+ Hits         4420     4424       +4     
+ Misses        747      745       -2     

Flag	Coverage Δ
rust	85.58% <100.00%> (+0.04%)	⬆️

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