Fix tokio-tungstenite 0.28.0 API compatibility

[Copilot]

The tokio-tungstenite 0.28.0 upgrade (PR #1054) changed WsMsg::Text from accepting String to Utf8Bytes.

Changes

Updated modeling-session/src/actor.rs to handle the new type:

• Outgoing messages: Added .into() conversion from String to Utf8Bytes when constructing WsMsg::Text
• Incoming messages: Changed text extraction to use .to_string() to convert Utf8Bytes to String

// Before
let ws_msg = WsMsg::Text(
    serde_json::to_string(&request).expect("..."),
);

// After
let ws_msg = WsMsg::Text(
    serde_json::to_string(&request).expect("...").into(),
);

// Before
WsMsg::Text(text) => Some(text),

// After
WsMsg::Text(text) => Some(text.to_string()),

Original prompt

Pull Request: #1054

Make a new PR that fixes the build, preserving the same functionality as before the crate bump.

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (dependabot/cargo/tokio-tungstenite-0.28.0@88d2689). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
modeling-session/src/actor.rs	0.00%	5 Missing ⚠️

Additional details and impacted files

@@                             Coverage Diff                              @@
##             dependabot/cargo/tokio-tungstenite-0.28.0    #1066   +/-   ##
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  Coverage                                             ?   29.24%           
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  Files                                                ?       35           
  Lines                                                ?     1737           
  Branches                                             ?        0           
============================================================================
  Hits                                                 ?      508           
  Misses                                               ?     1229           
  Partials                                             ?        0           

Flag	Coverage Δ
unittests	29.24% <0.00%> (?)

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