Lineage: symbol_lineage wasm export

[JonathanTurnock]

Part of #1 — data lineage canvas. Depends on the emit view.

Goal

Add a symbol_lineage export to crates/pseudoscript-wasm/src/lib.rs, mirroring symbol_scene (lib.rs:243 + symbol_scene_impl lib.rs:506):

#[wasm_bindgen]
pub fn symbol_lineage(modules_json: &str, fqn: &str) -> Result<String, JsError> { ... }

Returns the LineageScene JSON.

Test

Mirror symbol_scene_projects_a_container (lib.rs:832): symbol_lineage(workspace_json, "api::AccountData") returns a scene whose flow includes AccountRecord → AccountData. cargo test -p pseudoscript-wasm.

Rust authoring: use the idiomatic-rust skill.