perf/decoder quadratic scan

[lcweden]

This pull request introduces resumable string parsing to the JSON decoder, allowing it to correctly handle string values that are split across multiple input chunks. The main changes include the addition of the consumeStringResumable utility, updates to the Decoder and Cursor classes to track partial string parsing state, and comprehensive tests to ensure correctness for chunked and escaped string scenarios.

Resumable string parsing support:

• Added the consumeStringResumable function in src/utils/wire.ts to allow incremental/resumable parsing of string literals, supporting continuation across chunk boundaries and proper handling of escapes and UTF-8 validation. [1] [2] [3] [4]
• Updated the Decoder class in src/modules/decoder.ts to use consumeStringResumable and maintain an internal #offset for tracking partial string consumption, enabling correct parsing when string tokens are split across chunks. [1] [2] [3] [4] [5] [6]

Internal buffer management improvements:

• Enhanced the Cursor class in src/modules/cursor.ts to track buffer ownership and optimize how new byte chunks are appended, minimizing allocations and supporting efficient incremental parsing. [1] [2] [3]

Testing and validation:

• Added integration tests in tests/integration/decoder.test.ts to verify correct parsing of large strings, strings split across many chunks, escaped quotes at chunk boundaries, and full object values after chunked strings.
• Added unit tests for consumeStringResumable in tests/wire.test.ts, covering chunked string completion, escape handling, and deferred UTF-8 validation. [1] [2]

These changes collectively ensure that the JSON decoder can robustly parse arbitrarily chunked input streams, especially for large or escaped string values.