feat: Add experimental RISC-V packaging support

[AkarinServer]

⚠️ IMPORTANT / 注意事项

• DO NOT MERGE INTO MAIN YET / 暂勿合并至主分支: This feature is currently experimental and specifically tailored for RISC-V boards (e.g., Spacemit K1). It introduces packaging scripts that might need further refinement before being part of the standard release pipeline.
• Testing Required: Please verify on x64/arm64 to ensure no regression in standard build flows, although the changes are mostly isolated in new scripts.

Description

This PR introduces comprehensive support for building and packaging Netcatty for RISC-V architecture.

Key Changes

• New Packaging Script (scripts/pack-riscv.sh):

  • A unified script that handles frontend building, resource assembly, and .deb package generation.
  • Supports generating dual packages:
    • netcatty_*.deb: Standard build (with --no-sandbox).
    • netcatty-debug_*.deb: Debug build (with --disable-gpu --no-sandbox) for boards with GPU driver issues.
  • No app.asar: Deliberately packages the app as a plain directory structure to avoid compatibility issues on certain RISC-V environments.
  • Automatically prunes node_modules to remove dev dependencies.

• Config Helper (scripts/get-config.cjs):

  • Ensures packaging metadata (Version, Product Name, etc.) is consistent with package.json and electron-builder.json.

• Documentation (RISCV_README.md):

  • Added detailed instructions for downloading dependencies (Node.js, Electron RISC-V) and running the build process.

Motivation

RISC-V support for Electron apps is still maturing. This PR provides a "manual but automated" way to build Netcatty for these devices without relying on electron-builder's missing RISC-V support.

How to Test (on RISC-V Board)

1. Clone this branch.
2. Ensure npm and electron (v39.x riscv64) are available.
3. Run:

   ./scripts/pack-riscv.sh

4. Install the generated .deb package.

[AkarinServer]

该分支可以作为独立分支单独存在，并且自动触发main code copy。问题是，GitHub actions是没有RV编译的，或者说也不是没有，就是用simulator编译非常慢，很耗token。所以无法被编入CI。只能是谁需要就自己下载下来编译了。以及我的fork中有RV release，需要的可以自取。