* fix(sdk-android): add @JvmOverloads to Uatu.start
Java callers can now invoke start(application) without supplying a
Configuration, matching the Kotlin default-arg ergonomics.
* feat(agent): add protocol_version to HELLO handshake
ProtocolVersion=1 lives on Message and is set by Hello(). Server.Accept
rejects mismatches with a clear error. SDK upgrades that don't change
the wire format keep the same protocol_version; bump on breaking changes.
* test(agent): assert protocol_version in Hello round-trip
* feat(sdk-android): send protocol_version=1 in HELLO
Mirrors agent.ProtocolVersion on the Go side. Bump in lockstep with
the Go constant when the wire format breaks.
* chore(sample-app): pull @uatu/spec from npm next tag
Replaces the file: dep. Copy-paste users can now npm install against
the registry. The release workflow publishes pre-release tags to
npm dist-tag 'next', so the sample tracks the latest rc without
manual version bumps. Lockfile currently resolves to 0.0.1-rc3.