Add new plugin: Wallpaper switcher

[kavya-nama]

Plugin

• Id: kavya-nama/wallpaper-switcher
• New plugin
• Update to an existing plugin (version bumped in plugin.toml)

What it does

This plugin switches to the next wallpaper in the selected wallpaper catalogue in Noctalia settings.

External dependencies

None

Testing

• Tested on Niri
• Tested on Hyprland
• Tested on Sway
• Tested on another compositor:
• Noctalia version tested against: 5.0.0
• Plugin API level: 3

Screenshots / Videos

N/A

Checklist

• The directory name matches the part of id after the / in plugin.toml exactly.
• It ships plugin.toml, README.md, thumbnail.webp, and translations/en.json.
• README.md follows the
  README template, documents
  every entry id and dependency, and includes exact panel IPC commands and launcher prefixes where applicable.
• I created thumbnail.webp with the thumbnail generator.
• version follows semver and is bumped in this PR; plugin_api is the oldest API level this plugin requires.
• Every non-English translation in this PR uses a locale supported by Noctalia core, and I can read, write, and
  understand that language well enough to review and maintain it (no unreviewed machine/LLM translations).
• I did not edit catalog.toml; CI generates it.
• This PR touches exactly one plugin directory.

Code review attestation

Plugins run as trusted, unsandboxed Luau in the user's session. Confirm:

• The code is readable and not obfuscated, minified, or generated.
• It does not download and execute remote code.
• Every network call, filesystem write, and spawned process is something the description above accounts for.
• I have the right to publish this code under the license declared in plugin.toml.

[ItsLemmy]

1. non-blocking - wallpaper-switcher/thumbnail.webp:1

The rendered thumbnail labels the plugin "Audio • Widget", while the manifest and plugin behavior describe a wallpaper-switching bar widget. This user-visible category is inaccurate and could mislead catalog users. Regenerate the thumbnail with the correct wallpaper or utility category.

2. non-blocking - wallpaper-switcher/README.md:23

The documented command targets kavya-nama/wallpaper-switcher:switch with panel-toggle, but plugin.toml:12 declares switch only as a widget and defines no panel entry. The copy-paste command cannot resolve a plugin panel. Remove it or replace it with a command that accurately documents the supported interaction.

[kavya-nama]

Fixed the two issues:

1. Regenerated the thumbnail as well as updated plugin.toml with correct tags
2. Removed the invalid command from the README