Fix Node.js native library lookup in packaged Electron apps

[Andrey1994]

Motivation

• Packaged Electron apps could not locate BrainFlow native libraries because the Node.js binding hardcoded __dirname/../brainflow/lib, which does not resolve inside app.asar/packaged layouts.
• Provide a robust resolution strategy that works both in normal Node.js installs and in Electron production builds (including app.asar.unpacked and process.resourcesPath).

Description

• Add a shared resolver resolveLibPath() in nodejs_package/brainflow/lib_path.ts that builds candidate paths (including unpacked app.asar and common node_modules locations) and returns the first existing path or the original default as a fallback.
• Update the native loaders to use the new resolver by replacing the hardcoded path in BoardShim, DataFilter, and MLModel with resolveLibPath() in nodejs_package/brainflow/board_shim.ts, nodejs_package/brainflow/data_filter.ts, and nodejs_package/brainflow/ml_model.ts.
• Add a small TypeScript-friendly cast to safely access process.resourcesPath when present in Electron.

Testing

• Ran cd nodejs_package && npm run build and the TypeScript build completed successfully after adding the process cast. ✅
• Ran cd nodejs_package && npm run lint and linting failed with many existing formatting issues unrelated to this change; the failure is due to pre-existing repository-wide prettier violations and not introduced by this patch. ❌
• Verified the added resolver file nodejs_package/brainflow/lib_path.ts and that the three loaders now call resolveLibPath() instead of using the hardcoded __dirname path.

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[chatgpt-codex-connector]

Prioritize unpacked lib paths over app.asar paths

resolveLibPath() checks defaultLibPath first, so in Electron builds that use app.asar.unpacked it can still return an .../app.asar/... path when fs.existsSync reports that virtual ASAR entry as present. koffi.load/native dlopen requires a real filesystem path, so this selection causes native library loading to fail even when the unpacked copy exists; the unpacked candidates need to be searched before the default ASAR path.

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