feat(components): add missing languages to Code Text Splitter

[deepak0x]

Proposed changes

The Code Text Splitter node only listed the 16 languages natively supported by the JS @langchain/textsplitters package. The Python LangChain library supports many more languages that users have been requesting (C#, COBOL, Kotlin, TypeScript, etc). This PR adds 9 additional languages with custom separators ported from the Python LangChain source, while keeping existing languages on the native fromLanguage() path so there is zero regression risk.

New languages: c, csharp, cobol, elixir, haskell, kotlin, lua, powershell, ts

The dropdown is now sorted alphabetically for easier discovery.

Issue(s)

Closes #3752

How to test or reproduce

1. pnpm build && pnpm start
2. Create a new chatflow with a Code Text Splitter node
3. Open the Language dropdown and confirm the new languages appear (c, csharp, cobol, elixir, haskell, kotlin, lua, powershell, ts)
4. Select "csharp" and connect it to a document loader with C# source code
5. Verify the splitter chunks the code correctly along class/method/control-flow boundaries

Types of changes

• Bugfix (non-breaking change which fixes an issue)

Checklist

• I have read the CONTRIBUTING doc
• Lint and unit tests pass locally with my changes

[gemini-code-assist]

Code Review

This pull request expands the CodeTextSplitter to support a variety of new programming languages by introducing custom separators and updating the language selection options. The review feedback highlights several language-specific inaccuracies in the separator lists, such as the use of 'class' in C and 'implements' in C#, and recommends refining the fallback logic in the initialization method to ensure better error handling.

[deepak0x]

@HenryHengZJ — the Code Text Splitter was missing a bunch of languages that Python LangChain already supports. The JS @langchain/textsplitters only has 16, so I ported the separator definitions from the Python side and pass them as custom separators to RecursiveCharacterTextSplitter. The original 16 languages still go through fromLanguage() as before.

New languages: C, C#, COBOL, Elixir, Haskell, Kotlin, Lua, PowerShell, TypeScript.

The Gemini bot caught a few wrong keywords in the separator lists I ported — C doesn't have class (fixed to struct/union/enum), C# doesn't have implements, Elixir has no while, Kotlin has no case. Also changed the fallback to return a default splitter instead of throwing. All addressed in the latest push.