Task 414: Harden WASM Bindings Error Handling

Status: DONE

Summary

The WASM binding layer (solar-line-wasm/src/lib.rs) has 3 serde_wasm_bindgen::to_value().unwrap() calls that would cause WASM panics instead of graceful JsErrors on serialization failure. Additionally, lorentz_factor() wraps a core function that uses assert!() (panic) for v >= c, with no input validation in the WASM layer.

Rationale

• CLAUDE.md: "solar-line-wasm is strictly a binding layer (type conversion, error handling)"
• 39 other WASM functions already use Result<..., JsError> pattern
• A WASM panic crashes the entire module; a JsError allows JavaScript to handle gracefully
• lorentz_factor(v >= c) from JavaScript would crash the WASM module

Plan

1. Convert 3 to_value().unwrap() to Result<JsValue, JsError> returns
2. Add input validation to lorentz_factor WASM wrapper
3. Add tests for the error paths