Add pipeline-level endOfStream() method

Send a GStreamer EOS event directly to the pipeline element, enabling clean stream termination regardless of source type (hardware cameras, network streams, test sources).

Changes

• Native layer — Add end_of_stream method to the Pipeline C++ class, state-gated so it only sends when the pipeline is PLAYING or PAUSED
• TypeScript API — Expose endOfStream(): boolean on the Pipeline interface as an enumerable instance property
• Tests — Integration tests covering state dispatch, bus propagation, repeated calls, and post-stop behavior
• Example — examples/pipeline-eos.mjs demonstrating usage
• Docs — README updated with API reference and usage example
• Package — Renamed to @mantalabs/gst-kit, bumped to 0.2.8-alpha1

API

const pipeline = new Pipeline("videotestsrc ! fakesink");
await pipeline.play();

const sent = pipeline.endOfStream(); // true if EOS event was sent
await pipeline.stop();

Returns true when the pipeline is in a state that accepts events (PLAYING/PAUSED), false otherwise (NULL/READY/stopped).

Testing

• 7 integration tests validating state gating, synchronous return type, bus message propagation, idempotent repeated calls, and post-stop behavior