Add QBit data type examples for Node and Web clients

[Copilot]

Summary

Adds usage examples for the QBit data type introduced in ClickHouse 25.10. Verified that QBit columns round-trip cleanly through JSON formats despite the underlying Tuple(FixedString(N), ...) bit-plane layout — the server transparently serializes/parses them as the original Array(<element_type>), so no client-side workaround is needed for normal insert/select.

The only place users encounter non-UTF-8 bytes is when explicitly selecting a bit-plane subcolumn (vec.N); the example documents this and shows the hex() workaround.

• examples/{node,web}/coding/qbit.ts — create a QBit(Float32, 8) column, insert/select vectors via JSONEachRow, run an approximate search with L2DistanceTransposed, and demonstrate hex(vec.N) for raw bit-plane subcolumns. Sets allow_experimental_qbit_type=1 (required on 25.10, no-op on 26.x where QBit is GA).
• examples/README.md — new row in the coding/ table linking both files.

await client.command({
  query: `CREATE OR REPLACE TABLE chjs_qbit (id UInt64, vec QBit(Float32, 8))
          ENGINE MergeTree ORDER BY id`,
})
await client.insert({
  table: 'chjs_qbit',
  format: 'JSONEachRow',
  values: [{ id: 1, vec: [1, 2, 3, 4, 5, 6, 7, 8] }],
})
// Returns: [{ id: 1, vec: [1, 2, 3, 4, 5, 6, 7, 8] }]

Checklist

• A human-readable description of the changes was provided to include in CHANGELOG

Changelog

• New example: coding/qbit.ts for both Node and Web clients, demonstrating insert/select and L2DistanceTransposed search on QBit(...) columns via JSON formats, plus the hex() workaround for FixedString bit-plane subcolumns.

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