Rename misleading coverage variables in jsdoc-validation workflow

[Copilot]

TOTAL_JS and FILES_WITH_JSDOC were inaccurate names since the step counts both .js and .ts files and detects any /** */ doc comments, not strictly JSDoc.

Changes

• TOTAL_JS → TOTAL_SOURCE_FILES
• FILES_WITH_JSDOC → FILES_WITH_DOC_COMMENTS

TOTAL_SOURCE_FILES=$(find src/browser scripts \( -name "*.js" -o -name "*.ts" \) | ...)
FILES_WITH_DOC_COMMENTS=$(find src/browser scripts \( -name "*.js" -o -name "*.ts" \) ... -exec grep -l "/\*\*" {} \; | wc -l)

echo "📈 Documentation Coverage: $FILES_WITH_DOC_COMMENTS / $TOTAL_SOURCE_FILES files"

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