Add GROQ language support

[rexxars]

Add GROQ (Graph-Relational Object Queries) as a recognized data language with syntax highlighting for .groq files, JS/TS template literal injection, and markdown code block injection.

• Grammar source: sanity-io/groq-syntax (textmate-groq) (MIT licensed)
• Scopes: source.groq, groq-injection.js, groq-injection.markdown
• Samples: blog query, product filter, site navigation

Description

GROQ is an open query language for JSON-like data, created by Sanity.io and published under the OWFa 1.0 license since 2019. It is purpose-built for querying and transforming content in document stores, with first-class support for references, projections, and filtering.

GROQ is widely used across the Sanity ecosystem, which includes companies like Nike, Figma, Cloudflare, Spotify, Shopify, and Riot Games. The groq npm package sees 800k+ weekly downloads (24M+ annually).

While .groq files represent one surface for the language, the majority of GROQ is written as tagged template literals in JavaScript/TypeScript (groq`*[_type == "post"]`) and in markdown code blocks (```groq). The grammar source (sanity-io/groq-syntax) provides injection grammars for both of these, following the same pattern as GraphQL in Linguist (inline.graphql, inline.graphql.markdown.codeblock via graphql/graphiql).

A pull request to add an ace mode is open, but is yet to be reviewed/accepted - so using text for now until it has landed.

Usage evidence

Signal	Count	Search
groq template literals in TS	3,400+ files	search
groq template literals in JS	2,100+ files	search
```groq markdown blocks	630+ files	search
import groq in JS/TS	2,600+ files	search
.groq files (excl. forks)	200+ files / 40+ repos	search

The .groq extension meets the 200-file threshold for extensions that typically occur once per repository (like Makefile). The results show broad distribution across independent users and organizations - not concentrated in Sanity's own repos.

The broader surface (5,500+ template literal files, 630+ markdown code blocks) demonstrates that the community already treats GROQ as a distinct language deserving syntax highlighting.

VS Code extension

The Sanity VS Code extension has 50,000+ installs and has provided GROQ syntax highlighting since 2018. The grammar was recently extracted to a dedicated repo (sanity-io/groq-syntax) to support multiple editors and Linguist integration.

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.groq
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • Samples written for this PR, representative of common GROQ patterns (content queries with references, faceted filtering with parameters, conditional projections)
    • Sample license(s): MIT (same as Linguist)
  • I have included a syntax highlighting grammar: https://github.com/sanity-io/groq-syntax
  • I have added a color
    • Hex value: #fa84ff
    • Rationale: Magenta from GROQ's brand palette.
  • I have updated the heuristics to distinguish my language from others using the same extension.
    Not needed - .groq is not used by any other language.