Add Kotodama language grammar and samples

[takemiyamakoto]

Description

Add Kotodama as a first-class language in Linguist, mapping .ko files to the TextMate scope source.kotodama.

This PR includes:

• a syntax-highlighting grammar sourced from https://github.com/takemiyamakoto/language-kotodama
• a new Kotodama entry in lib/linguist/languages.yml
• real .ko samples from the public Hyperledger Iroha repository

This is opened as a draft because the current public usage counts appear to be below Linguist's usual threshold for new languages. I wanted to provide a concrete implementation for maintainers to evaluate, but I am explicitly not claiming that the adoption bar has been met.

Checklist:

• I am adding a new extension to a language.

• 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+extension%3Ako+seiyaku
      • https://github.com/search?type=code&q=NOT+is%3Afork+extension%3Ako+kotoage
      • https://github.com/search?type=code&q=NOT+is%3Afork+extension%3Ako+%22register_trigger%22
    • Authenticated API counts observed while preparing this draft on 2026-03-31:
      • extension:ko seiyaku NOT is:fork -> 67
      • extension:ko kotoage NOT is:fork -> 62
      • extension:ko "register_trigger" NOT is:fork -> 2
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/hyperledger-iroha/iroha/blob/main/crates/kotodama_lang/src/samples/irohaswap.ko
      • https://github.com/hyperledger-iroha/iroha/blob/main/crates/kotodama_lang/src/samples/mint_rose_trigger.ko
      • https://github.com/hyperledger-iroha/iroha/blob/main/crates/kotodama_lang/src/samples/zk_vote_and_unshield.ko
    • Sample license(s):
      • Apache-2.0
  • I have included a syntax highlighting grammar: https://github.com/takemiyamakoto/language-kotodama
  • I have added a color
    • Hex value: #C26E2D
    • Rationale: chosen to give Kotodama a distinct warm tone rather than reusing Kotlin/Rust-adjacent colors
  • I have updated the heuristics to distinguish my language from others using the same extension.

• I am fixing a misclassified language

• I am changing the source of a syntax highlighting grammar

• I am updating a grammar submodule

• I am adding new or changing current functionality

  • I have added or updated the tests for the new or changed functionality.
    • Manual validation run locally instead:
      • bundle _2.7.2_ exec ruby -Ilib -e 'require "linguist"; ["samples/Kotodama/irohaswap.ko","samples/Kotodama/mint_rose_trigger.ko","samples/Kotodama/zk_vote_and_unshield.ko"].each { |p| blob = Linguist::FileBlob.new(p); puts "#{p}: #{blob.language&.name}" }'
      • all three sample files classified as Kotodama

• I am changing the color associated with a language