docs(examples): add KPipe.bytes example (refs #166)

[eschizoid]

Summary

The audit in #166 flagged that KPipe.bytes(topic, props) was the only bundled format on the fluent facade without a corresponding examples/ module. JSON, Avro, Protobuf, and the multi/demo paths all had complete reference apps; the raw-bytes path did not.

This PR adds examples/bytes to close that gap.

What the example teaches

• KPipe.bytes(topic, props).toCustom(MessageSink<byte[]>).start() — the simplest possible end-to-end raw-bytes consumer.
• Demonstrates that the pipeline can stay in byte[] end-to-end with no format SerDe — useful for proxying, raw archival, or pre-format inspection where the consumer doesn't care about the payload structure.
• The custom MessageSink<byte[]> logs each record's length plus a short hex preview, mirroring what bytesConsoleSink() does internally but inlined so the reader can see how toCustom(...) plugs in.

Structure

Copied from examples/json/:

• examples/bytes/build.gradle.kts — same shape as the json module, minus the JSON format dep (raw byte[] needs no format module — MessageFormat.bytes() lives in kpipe-core, transitively pulled by kpipe-api).
• examples/bytes/src/main/java/io/github/eschizoid/kpipe/App.java — AppConfig.fromEnv() + KafkaConsumerConfig + a 5-line MessageSink<byte[]> lambda.
• settings.gradle.kts — registers examples:bytes.

Refs #166 (does not close — that issue tracks broader audit follow-ups).

[eschizoid]

@copilot please review

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.08%. Comparing base (50d524e) to head (6a1d74f).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #183   +/-   ##
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  Coverage     77.08%   77.08%           
  Complexity      752      752           
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  Files            72       72           
  Lines          2858     2858           
  Branches        355      355           
=========================================
  Hits           2203     2203           
  Misses          489      489           
  Partials        166      166           

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