Add generated TUS protocol contract canary

[kvz]

Why: this is the Java companion canary for the API2 contract generator work. API2 owns the TUS protocol contract; this PR proves tus-java-client can consume generated protocol facts without duplicating wire knowledge in the Java repo.

What changed:

• add generated TusProtocol.DEFAULT_PROTOCOL_VERSION from the API2 TUS wire contract
• source TusClient.TUS_VERSION from that generated constant
• add a generated protocol contract fixture for operations, headers, responses, wire versions, and high-level feature facts
• add a small handwritten test proving the runtime constant and singleUploadLifecycle feature consume the generated facts

Validation:

• ./gradlew clean check --no-daemon
• api2/bin/cli.ts contracts tus-sdks --no-motd --platform java --sdk-root ../tus-java-client --compare-existing

Companion PRs:

• API2 generator and contract source: https://github.com/transloadit/api2/pull/7928
• tus-js-client: Mark protocol versions as generated tus-js-client#872
• tus-go-client: Add generated TUS protocol canary tus-go-client#6
• tus-py-client: Add generated TUS protocol canary tus-py-client#114

[kvz]

Closing this draft-created PR and reopening as a normal PR so the existing GitHub Actions opened trigger has a clean event to run from.