Add oldbook-theme extension

[gko]

No description provided.

[gko]

@maxdeviant I might be wrong but I think that CI is failing because of #3079:

Error: Command failed: ./zed-extension --scratch-dir ./scratch --source-dir extensions/nyxvamp-theme --output-dir output
[2025-07-29T21:27:47Z INFO  zed_extension] loading extension manifest
[2025-07-29T21:27:47Z INFO  zed_extension] compiling extension
[2025-07-29T21:27:47Z INFO  extension::extension_builder] finished compiling extension /home/runner/work/extensions/extensions/extensions/nyxvamp-theme
[2025-07-29T21:27:47Z WARN  theme] Theme "NyxVamp Veil" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.
[2025-07-29T21:27:47Z WARN  theme] Theme "NyxVamp Obsidian" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.
[2025-07-29T21:27:47Z WARN  theme] Theme "NyxVamp Radiance" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.
[2025-07-29T21:27:47Z INFO  zed_extension] loaded theme family NyxVamp
Error: Theme "NyxVamp Veil" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.

    at genericNodeError (node:internal/errors:984:15)
    at wrappedFn (node:internal/errors:538:14)
    at ChildProcess.exithandler (node:child_process:422:12)
    at ChildProcess.emit (node:events:524:28)
    at maybeClose (node:internal/child_process:1104:16)
    at ChildProcess._handle.onexit (node:internal/child_process:304:5) {
  code: 1,
  killed: false,
  signal: null,
  cmd: './zed-extension --scratch-dir ./scratch --source-dir extensions/nyxvamp-theme --output-dir output'
}

Node.js v20.19.4
 ELIFECYCLE  Command failed with exit code 1.
Error: Process completed with exit code 1.

[maxdeviant]

@maxdeviant I might be wrong but I think that CI is failing because of #3079:

Error: Command failed: ./zed-extension --scratch-dir ./scratch --source-dir extensions/nyxvamp-theme --output-dir output
[2025-07-29T21:27:47Z INFO  zed_extension] loading extension manifest
[2025-07-29T21:27:47Z INFO  zed_extension] compiling extension
[2025-07-29T21:27:47Z INFO  extension::extension_builder] finished compiling extension /home/runner/work/extensions/extensions/extensions/nyxvamp-theme
[2025-07-29T21:27:47Z WARN  theme] Theme "NyxVamp Veil" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.
[2025-07-29T21:27:47Z WARN  theme] Theme "NyxVamp Obsidian" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.
[2025-07-29T21:27:47Z WARN  theme] Theme "NyxVamp Radiance" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.
[2025-07-29T21:27:47Z INFO  zed_extension] loaded theme family NyxVamp
Error: Theme "NyxVamp Veil" is using a deprecated style property: scrollbar_thumb.background. Use `scrollbar.thumb.background` instead.

    at genericNodeError (node:internal/errors:984:15)
    at wrappedFn (node:internal/errors:538:14)
    at ChildProcess.exithandler (node:child_process:422:12)
    at ChildProcess.emit (node:events:524:28)
    at maybeClose (node:internal/child_process:1104:16)
    at ChildProcess._handle.onexit (node:internal/child_process:304:5) {
  code: 1,
  killed: false,
  signal: null,
  cmd: './zed-extension --scratch-dir ./scratch --source-dir extensions/nyxvamp-theme --output-dir output'
}

Node.js v20.19.4
 ELIFECYCLE  Command failed with exit code 1.
Error: Process completed with exit code 1.

This branch needed to be updated with main.

Now it looks like it is failing over some missing metadata.

[gko]

@maxdeviant seems like CI was trying to validate vscode theme as well, so I moved it to a separate folder

[maxdeviant]

Thanks!