Fix 14 bugs found during code audit

[JordanBoltonMN]

Bug fixes:

• Pattern regex escaping (patterns.ts)
• StringUtils grapheme boundary (stringUtils.ts)
• Token kind mismatch (token.ts)
• Lexer off-by-one (lexer.ts)
• LexerSnapshot cache invalidation (lexerSnapshot.ts)
• Context node cleanup (contextUtils.ts)
• copyState currentContextNode isolation (parseStateUtils.ts)
• NodeIdMapIterator bounds check (nodeIdMapIterator.ts)
• Validator type predicates (combineOperatorsAndOperands.ts)
• Disambiguation indent normalization (disambiguationUtils.ts)
• ParserUtils error propagation (parserUtils.ts)
• Tokenizer incremental sync (tokenizerIncremental.test.ts)
• Redundant ParseContextUtils.newState() call (parseStateUtils.ts)
• Package version bump (package.json)

All tests pass (779 passing, 1 pending).
Lint clean (0 errors, 0 warnings).

[Copilot]

Pull request overview

This PR addresses a set of correctness bugs found during a code audit across the lexer, parser, and shared utilities, and adds/updates regression tests to lock in the fixes. It also bumps the package version to reflect the set of bugfixes.

Changes:

• Fixes multiple lexer/parser correctness issues (token kinds, incremental retokenization, snapshot position accounting, disambiguation error handling, node iteration bounds, parse-state copying isolation).
• Corrects several shared utility regex/string edge cases (numeric exponent sign, whitespace regex, identifier character classes, escaped-quote scanning).
• Adds focused regression tests covering the reported bugs, plus bumps the package version.

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/test/libraryTest/tokenizer/tokenizerIncremental.test.ts	Updates expected scope name for text literal token content.
src/test/libraryTest/parser/parseNodeIdMapUtils.test.ts	Adds regression tests ensuring copyState isolates currentContextNode references.
src/test/libraryTest/parser/parseBehavior.test.ts	Ensures invalid parseBehavior hits an invariant path; adds type-directive regression coverage (one test marked pending).
src/test/libraryTest/lexer/lexSimple.test.ts	Adds regression tests for numeric exponent escaping and end-of-input .. handling; adds whitespace-pattern regression tests.
src/test/libraryTest/lexer/lexMultilineTokens.test.ts	Adds regression test validating LineTokenKindAdditions.TextLiteralContent enum value matches its member name.
src/test/libraryTest/lexer/lexIncremental.test.ts	Adds regression test ensuring incremental retokenization does not drop lines.
src/test/libraryTest/lexer/lexerSnapshotCache.test.ts	Adds regression tests for codeUnit correctness in grapheme position computations.
src/test/libraryTest/language/astUtils.test.ts	Adds tests covering validator operand type predicates for nested as expressions and equality operands.
src/test/libraryTest/common/stringUtils.test.ts	Adds tests for consecutive/multiple escaped quotes in findQuotes.
src/test/libraryTest/common/cancellationToken.test.ts	Adds tests verifying CounterCancellationToken consumes exactly one count per call.
src/powerquery-parser/parser/parseState/parseStateUtils.ts	Ensures copyState uses the copied contextState and rebinds currentContextNode to the copied node instance.
src/powerquery-parser/parser/parsers/combinatorialParserV2/combineOperatorsAndOperands.ts	Fixes validator type predicates for as and equality/relational operand typing.
src/powerquery-parser/parser/parser/parserUtils.ts	Makes the parseBehavior default branch explicitly throw via Assert.isNever.
src/powerquery-parser/parser/nodeIdMap/nodeIdMapIterator.ts	Fixes sibling bounds check to correctly return undefined only when out of range.
src/powerquery-parser/parser/disambiguation/disambiguationUtils.ts	Improves catch handling to validate Error and rethrow cancellation errors before restoring checkpoints.
src/powerquery-parser/parser/context/contextUtils.ts	Fixes isNodeKind runtime behavior for union input (array vs single kind).
src/powerquery-parser/lexer/lexerSnapshot.ts	Fixes grapheme position codeUnit to reflect token start rather than token end.
src/powerquery-parser/lexer/lexer.ts	Fixes incremental retokenization early-exit to not drop the current line.
src/powerquery-parser/language/token.ts	Fixes TextLiteralContent enum value mismatch ("TextContent" → "TextLiteralContent").
src/powerquery-parser/common/stringUtils.ts	Fixes findQuotes loop control for escaped quote handling.
src/powerquery-parser/common/patterns.ts	Fixes regexes for identifier chars, whitespace, and numeric exponent sign matching.
package.json	Bumps package version to 0.20.0.
package-lock.json	Updates lockfile version fields to 0.20.0.

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