…plugin

The CoreServices framework reference was added to fix file_system package
compilation on macOS (PR jetify-com#2462), but is no longer needed with the new Darwin
SDK pattern introduced in nixpkgs.

With the updated Darwin stdenv, the Apple SDK (including CoreServices) is
now automatically provided, making the explicit framework reference obsolete.
The old pattern using darwin.apple_sdk_11_0 has been removed from nixpkgs,
causing installation failures on macOS.

This change removes the packages section entirely and bumps the plugin
version to 0.0.2.

Fixes jetify-com#2705
Fixes jetify-com#2557

## Summary

Fixes the elixir plugin to work with the new Darwin SDK pattern in
nixpkgs by removing the explicit
`darwin.apple_sdk.frameworks.CoreServices` dependency.

## How was it tested?

Tested on **macOS (darwin-arm64)**:

1. **Built devbox locally**: `devbox run build`
2. **Added elixir package**: `devbox add elixir`
   - ✅ No `darwin.apple_sdk_11_0 has been removed` error
   - ✅ Successfully installed Elixir 1.18.1 with Erlang/OTP 27

<img width="736" height="37" alt="image"
src="https://github.com/user-attachments/assets/5808dfab-b525-4816-a19c-69ba8070dfaa"
/>

3. **Verified elixir functionality**: `elixir --version` successfully
showed version information

<img width="1506" height="272" alt="image"
src="https://github.com/user-attachments/assets/37230f7f-1b2a-42c4-83da-c8db28b70984"
/>

4. **Tested the original issue** - compiling `file_system` package (used
by Phoenix for Live Reload):
   - Created a Mix project with `file_system` dependency
   - ✅ Successfully compiled the native macOS FSEvents watcher
   - Log output: `Compiling file system watcher for Mac... Done.`

<img width="609" height="203" alt="image"
src="https://github.com/user-attachments/assets/b13e60c5-1c38-417a-926c-fa4d358dc5b6"
/>

This confirms that the CoreServices framework is now automatically
available through the new Darwin stdenv, and the explicit
`darwin.apple_sdk.frameworks.CoreServices` package reference is no
longer needed.

## Background

The elixir plugin currently includes
`darwin.apple_sdk.frameworks.CoreServices` in its packages section
(added in
#2462 (comment)
to fix `file_system` package compilation on macOS). However, this
reference uses the old Darwin SDK pattern that has been removed from
nixpkgs.

As documented in
[NixOS/nixpkgs#354146](NixOS/nixpkgs#354146),
nixpkgs has migrated to a new Darwin SDK pattern where:
- The stdenv now provides a default SDK automatically
- Framework dependencies like CoreServices are bundled in the SDK
- Explicit framework references using the old `darwin.apple_sdk_11_0`
pattern cause errors

## Changes

- Removed the `packages` section from `plugins/elixir.json`
- Bumped plugin version from `0.0.1` to `0.0.2`

The `file_system` package will continue to work on macOS because
CoreServices is now automatically available through the new Darwin
stdenv.

Fixes #2705
Fixes #2557