Add platform support note and existing file handling documentation to README and skill docs, clarifying Windows 11-only testing, per-script ffmpeg/ffprobe requirements, and file replacement behavior with -y flag across Clone-Image.md, Clone-Video.md, Compare-Videos.md, Crop-Clips.md, Get-VideoAudio.md, SKILL.md and index.md

skill/Clone-Video.md

@@ -456,6 +456,13 @@ The output container is selected from the `-Target` file extension. Each contain
 - **WebM encoding is slow.** `libvpx-vp9` is much slower than `libx264`; the chosen `cpu-used 2 -row-mt 1` settings strike a reasonable balance, but expect significantly longer rendering times than MP4.
 - **MKV stream-copy is greedy.** Because MKV accepts almost any codec, MKV output usually involves no re-encoding at all and is the fastest target for re-containerising downloads.
 
+## Existing Files
+
+- An existing `-Target` video is **replaced** without a prompt. ffmpeg runs with `-y`, so the old file is lost. Use `-WhatIf` first, or write to a new name.
+- The same applies to the image-to-video and PNG-sequence modes, and to a PNG that `-Sequence` would overwrite.
+- The folder that contains `-Target` must already exist. The script stops with an error instead of creating it.
+- The temporary concat list used for PNG sequences is deleted after the run.
+
 ## Safe Execution
 
 This script supports `-WhatIf` and `-Confirm` for safe execution: