feat(processors): auto-detect delimiter for CSV/TSV/DSV files

[igorDykhta]

• Add automatic delimiter detection to processCsvData so that files using tabs, semicolons, or pipe characters as delimiters are parsed correctly without requiring any user configuration.
• instead of the stale feat(processors): auto-detect delimiter for CSV/TSV/DSV files #3334 with extra tests and fixes

[Copilot]

Pull request overview

Adds delimiter auto-detection to the processors CSV path so tab/semicolon/pipe-delimited text can be parsed without user configuration, and updates the UI’s accepted extensions accordingly.

Changes:

• Introduces detectDelimiter() and uses it in processCsvData() to select the correct d3-dsv parser (CSV/TSV/custom DSV).
• Extends default accepted file extensions/formats to include tsv and dsv.
• Adds extensive unit tests covering delimiter detection and parsing behavior across multiple delimiters and edge cases.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/node/utils/data-processor-test.js	Adds coverage for detectDelimiter and processCsvData parsing of TSV/SSV/PSV and edge cases.
src/reducers/src/vis-state-selectors.ts	Adds tsv/dsv to default extension + format lists exposed to the UI.
src/processors/src/data-processor.ts	Implements delimiter detection and switches CSV parsing to the detected DSV parser.

Comments suppressed due to low confidence (1)

src/processors/src/data-processor.ts:167

• This error message now triggers for TSV/semicolon/pipe-delimited inputs as well, but it still says “CSV is empty”. Please update it to a delimiter-agnostic message (e.g. “DSV is empty” / “delimited text is empty”) so users get accurate feedback.

    if (!Array.isArray(parsedRows) || parsedRows.length < 2) {
      // looks like an empty file, throw error to be catch
      throw new Error('process Csv Data Failed: CSV is empty');
    }

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