Make SQLite runtime loading safe for Node-targeted bundles

[Copilot]

Node-targeted CLIs consuming @wgtechlabs/config-engine could still fail at runtime because bundled output retained a bun:sqlite import. This change keeps Bun as the primary runtime while making the package safe to load from Node-targeted artifacts.

• Runtime adapter loading

  • Replace the static Bun SQLite import path with runtime-only resolution.
  • Keep Node on better-sqlite3 via the existing adapter path.
  • Preserve the Bun-first behavior without leaking bun:* imports into Node bundles.

• Bundling regression coverage

  • Add a focused runtime test that bundles a small entrypoint for target: "node".
  • Assert the emitted bundle does not contain a static bun:sqlite import and can be loaded by Node.

• Documentation

  • Clarify that the Bun SQLite backend is loaded only at runtime on Bun, so Node-targeted bundles can consume the package safely.

import { createRequire } from "node:module";

const runtimeRequire = createRequire(import.meta.url);

function openBunDatabase(filepath: string) {
	const { Database } = runtimeRequire(getBunSqliteSpecifier());
	return new Database(filepath);
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>Node-targeted npm CLIs fail because the package imports bun:sqlite</issue_title>
<issue_description>## Summary
Using @wgtechlabs/config-engine in a package that is built for Node and published to npm can fail at runtime because the package imports bun:sqlite.

In practice this makes the package Bun-only for bundled Node CLI releases, even when the consumer application itself targets Node.

Repro

Consumer build:

bun build src/index.ts --outfile dist/index.js --target node
node dist/index.js --version

Actual result

Node fails during module loading with:

Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only URLs with a scheme in: file, data, and node are supported by the default ESM loader. Received protocol 'bun:'

Why this matters

I hit this in a released npm CLI because Bun bundled the dependency graph into a Node-targeted artifact, and the resulting build still contained bun:sqlite imports.

That means the package is not currently safe to consume from a published Node CLI unless the consumer is also effectively Bun-only.

Expected result

One of these should happen:

1. The package provides a Node-safe backend or conditional runtime adapter.
2. The package clearly documents that it is Bun-only.
3. The package exposes a storage abstraction that allows Node consumers to avoid bundling bun:* imports.

Notes

I am happy to help test a fix from the consumer side.
</issue_description>

<agent_instructions>Let's add support to both node and bun, but primarily we support bun.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Node-targeted npm CLIs fail because the package imports bun:sqlite #1

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