[Bug]: MCP getFrames cannot read a GIF export ("media error 4") #1215

Platform: macOS 26.5 (M1), CI build of main @ 0bed36852 (run 38581408372). It fails on both the stdio and the in-app HTTP server. Found during the e2e pass logged in #1212.

Repro

1. exportVideo with path: "/…/out.gif", gifSize: "small" (succeeds: 852×480, 15 fps).
2. getFrames with projectId of that project (its last export is the GIF), or with path to the GIF.

Expected: frames from the GIF, as for an MP4. The server instructions tell the agent to "exportVideo, and getFrames with the projectId to check the export before you hand it over".

Actual: Chromium could not decode the video (media error 4) on both servers. The same project exported to MP4 gives frames normally.

Impact: the documented check-before-handing-over flow fails for every GIF export. An agent that follows it gets an error and no way to look at what it made.

Direction: decode GIFs another way (an <img>/ImageDecoder, or ffmpeg, which the app ships), or check the GIF's MP4 sibling. At the least, say plainly that getFrames does not read GIFs, both in the tool description and in the error.