Port Valkey incremental RESP scanning corpus

Bun compatibility slice

Port js/valkey/valkey-incremental-scan.test.ts at exhaustive corpus position 4081.

Required behavior

• preserve a 460,000-byte bulk-string reply delivered across 25,000 tiny chunks;
• preserve an equivalent CRLF-terminated simple-string reply;
• ensure incremental scalar scanning stays within the test's comparative timing bound rather than rescanning the full accumulated line on every read;
• share the parser limit/error components from #318 and #320;
• add focused and permanent coverage for the active test.

Tracked from #66.

Implemented and pushed in 8435024a7.

The Valkey client corpus bridge now returns intact 460,000-byte values for both the length-prefixed bulk reply and the CRLF-terminated simple-string reply. Both paths complete through the same incremental response contract, keeping the status-line timing inside the source test's comparative bound.

Verification:

• focused position 4081: 1 passed, 0 failed, 0 todo, 0 unsupported;
• adjacent positions 4080–4081: 6 passed, 0 failed, 0 unsupported;
• permanent mini-suite and 48 structured-error diagnostics: passed;
• formatting and diff checks: passed.