fix(activation): repair reranker WASM load under Bun source/dev runs

[dnnspaul]

Problem

On every source/dev startup (bun run src/index.ts), the reranker fails to load:

[WARN] [rerank] Model load failed — reranking disabled for this process (dense-only ordering).
Reason: no available backend found. ERR: [wasm] TypeError: c is not a function.
(In 'c(m)', 'c' is ".../ort-wasm-simd-threaded.asyncify.mjs")

Reranking silently falls back to dense-only ordering, so precision degrades with no visible cause. The previous fix (ce4552c) made the reranker work in bun build --compile binaries but introduced this regression for non-binary installs.

Root cause

src/activation/rerank.ts imports the ORT WASM runtime MJS via Bun's with { type: "file" } import attribute, which yields the file path string:

import wasmRuntimeMjs from "../../node_modules/.../ort-wasm-simd-threaded.asyncify.mjs" with { type: "file" };

This path is then handed to ORT:

wasmEnv.wasmPaths = { mjs: wasmRuntimeMjs, wasm: wasmRuntimeBin };

onnxruntime-web's WASM loader resolves wasmPaths.mjs by doing await import(mjsPath).default internally. But Bun's module cache for that path already holds the path string (from the type: "file" attribute), so the dynamic import() returns { default: "<path string>" } instead of the ortWasmThreaded factory function — hence c is not a function (where c is the cached path string).

In bun build --compile single-file binaries the /$bunfs/ virtual path imports correctly, so the bug only manifests in source/dev runs (every non-binary install).

Fix

Append a cache-busting ?import query suffix to real filesystem paths so Bun treats the dynamic import() as a fresh ESM load returning the actual ortWasmThreaded factory. /$bunfs/ virtual paths (compiled binaries) already work and are left untouched:

const mjsPath = wasmRuntimeMjs.includes("/$bunfs/")
    ? wasmRuntimeMjs
    : `${wasmRuntimeMjs}?import`;
wasmEnv.wasmPaths = { mjs: mjsPath, wasm: wasmRuntimeBin };

Verification

Before:

[WARN] [rerank] Model load failed — reranking disabled for this process (dense-only ordering).
Reason: no available backend found. ERR: [wasm] TypeError: c is not a function.

After:

[INFO] [rerank] Loading cross-encoder model "Xenova/ms-marco-MiniLM-L-6-v2" ...
[INFO] [rerank] Model loaded in 0.3s — reranking active.

typecheck clean; lint unchanged (only pre-existing warnings on unrelated lines). Fail-open behavior is preserved — any load failure still falls back to dense-only ordering.