feat(video): add native AVC/HEVC and synchronized AAC MP4 streaming

packages/video/docs/native-video.mdadded+25-0

Changes to packages/video/docs/native-video.md

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	1	+# Header-checked native video adapter
	2	+
	3	+`codecs/video/native_encoder.{c,h,zig}` compiles the x264/x265 boundary against
	4	+installed vendor headers. Only Home-owned scalar configuration and borrowed
	5	+length-prefixed packet data cross the interface. The Zig wrapper validates input
	6	+geometry, timestamps and encode/drain state. Link the C source and libx264/libx265.
	7	+
	8	+`Encoder.requestKeyframe()` / `home_encoder_request_keyframe` requests an IDR for
	9	+the next submitted input. Requests coalesce. This supports independently decodable
	10	+recording splits without waiting for the regular GOP interval. Inspect emitted
	11	+packet timestamps and key flags before switching outputs: buffered AVC output
	12	+can precede the newly requested IDR. Keep headers outside packet history and
	13	+remux each segment with a fresh sample description and a rebased timeline.
	14	+
	15	+Use requests only on an active encoder before draining, serialize every operation,
	16	+and consume borrowed output before another adapter call. The Zig wrapper rejects
	17	+requests after drain/failure. A request neither drains nor resets the encoder.
	18	+
	19	+The standalone `tests/native_encoder_idr.zig` imports this module as `encoder` and
	20	+links its compiled C boundary. Its regression encodes eight frames under GOP100,
	21	+forces IDRs at inputs 3 and 6, checks actual AVC/HEVC IDR NAL types and packet keys,
	22	+counts every delayed/flushed frame, and rejects requests after drain. It passes
	23	+on Zig 0.15.2 and Home's installed 0.17 development toolchain with x264/x265.
	24	+zig-camera additionally remuxes split files and pre-roll snapshots and validates
	25	+them with independent decoders. No FFmpeg or Libav is used in this path.