CBL-8080: Add JNI support for per-transport MultipeerReplicator status

[pasin]

• Implement JNI for per-transport status notifications.
• Implement JNI for getting status by transport.
• Clean up JNI API comments in the header file.

[Copilot]

Pull request overview

Adds JNI plumbing to expose per-transport MultipeerReplicator status to the Java layer, including a native getStatus API and updated callback wiring, plus small related constant/header comment updates.

Changes:

• Introduces PeerSyncProtocols.NONE and adds protocol documentation in C4Constants.
• Updates the multipeer JNI callback onSyncStatusChanged to pass a new C4PeerSyncStatus Java object, and adds a native getStatus(peer, protocol) implementation.
• Cleans up/updates the generated JNI header comments for NativeC4MultipeerReplicator.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
common/main/java/com/couchbase/lite/internal/core/C4Constants.java	Adds/clarifies peer sync protocol constants, including a new NONE value.
common/main/cpp/native_c4multipeerreplicator.cc	Wires per-transport status through JNI via C4PeerSyncStatus, updates callback signature, and adds getStatus.
common/main/cpp/com_couchbase_lite_internal_core_impl_NativeC4MultipeerReplicator.h	Updates JNI header comment blocks to match the current native API (including new getStatus).

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