Add local video publisher & subcriber examples

[chenosaurus]

adding examples/local_video to demonstrate publishing & subscribing to video tracks using the Rust SDK.

[Copilot]

Pull request overview

This PR adds two comprehensive examples demonstrating local video capture and streaming with the LiveKit Rust SDK: a publisher that captures frames from a local camera and publishes them to a LiveKit room, and a subscriber that connects to a room and renders received video in a window with GPU acceleration.

Key changes:

• Publisher example with camera capture, format conversion (YUYV/MJPEG/RGB24 to I420), and H.264/H.265 codec support
• Subscriber example with GPU-accelerated YUV rendering using WGPU/egui and simulcast layer controls
• Enhanced yuv-sys build script to detect and enable libjpeg/libjpeg-turbo for MJPEG fast-path decoding

Reviewed changes

Copilot reviewed 8 out of 10 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
yuv-sys/build.rs	Adds pkg-config detection for system libjpeg to enable MJPEG fast-path conversion in libyuv
yuv-sys/Cargo.toml	Adds pkg-config dependency for build-time library detection
examples/local_video/Cargo.toml	New example package configuration with required dependencies for camera capture, video processing, and GPU rendering
examples/local_video/README.md	Documentation for both publisher and subscriber examples with usage instructions
examples/local_video/src/publisher.rs	Complete publisher implementation with camera capture, format detection/conversion, and LiveKit video track publishing
examples/local_video/src/subscriber.rs	Complete subscriber implementation with video stream reception, GPU rendering, and simulcast controls
examples/local_video/src/yuv_shader.wgsl	WGSL shader for YUV to RGB conversion and rendering in the subscriber
Cargo.toml	Adds local_video example to workspace members
Cargo.lock	Lock file updates for new dependencies
.gitignore	Adds .cursor IDE directory to ignore list

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Inconsistent indentation: these lines use 3 spaces while lines 40-45 above use 4 spaces (with the exception of line 45). The indentation should be consistent throughout the command blocks.

Suggested change

	--api-secret YOUR_SECRET
	# subscribe to a specific participant's video only
	cargo run -p local_video --bin subscriber -- \
	--room-name demo \
	--identity viewer-1 \
	--participant alice
	--api-secret YOUR_SECRET
	# subscribe to a specific participant's video only
	cargo run -p local_video --bin subscriber -- \
	--room-name demo \
	--identity viewer-1 \
	--participant alice