Add Jac language support

[MalithaPrabhashana]

Summery:

Added official support for the Jac programming language to GitHub Linguist, including language definition, syntax-highlighting grammar, and representative sample files.

Description

This pull request adds Jac language detection and highlighting by:

• Adding a new Jac entry to languages.yml
• Vendoring the Jac TextMate grammar (jaseci-labs/jac-linguistic-syntax)
• Adding example .jac files under samples/Jac/ for detection validation

Checklist:

• I am adding a new language.
  • The .jac extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension: 4.1k files
      • https://github.com/search?q=walker+path%3A*.jac&type=code
      • https://github.com/search?q=node+path%3A*.jac&type=code
      • https://github.com/search?q=with+entry+path%3A*.jac&type=code
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • LittleX
      • Jac GPT
    • Sample license(s): MIT License
  • I have included a syntax highlighting grammar: https://github.com/jaseci-labs/jac-linguistic-syntax
  • I have added a color
    • Hex value: #FC792D
    • Rationale: Matches the Jac logo color for consistency. Webpage
  • I have updated the heuristics to distinguish my language from others using the same extension.

[lildude]

The extension of the new language is used in hundreds of repositories on GitHub.com.

* Search results for each extension:
  
  * https://github.com/jaseci-labs/Agentic-AI/blob/main/jac-gpt/server/server.jac
  * https://github.com/jaseci-labs/Agentic-AI/blob/main/task_manager/byllm/BE/v1/main.jac
  * https://github.com/jaseci-labs/jaseci/blob/main/jac/examples/littleX/littleX.jac

This should be a GitHub search URL that is used to prove the popularity of your language, not a list of files. We even provide you with a hint which you just need to modify. Please correct this.

• Sample license(s):

Please state the license, not link to it. And we only need the license for the samples as the PR includes a cached copy of the grammar license.

As for your samples. We need real-world samples. Not contrived examples or demonstrations of concepts of the language. And two to three is plenty.

[MalithaPrabhashana]

@lildude Hey, I’ve updated the PR description as requested. Could you please check if everything is now in the expected format?

[MalithaPrabhashana]

@lildude Samples also updated by adding 2 real applications we created.