Move docs/ package mirror into document-navigator plugin

Relocate the ~6k-file docs tree from the repo root into
plugins/document-navigator/docs/ so the plugin is self-contained and
portable. docs/superpowers/ (specs and plans) stays at the repo root.

Moved via cp+rm rather than git mv because directory rename() fails with
EPERM on this WSL /mnt DrvFs mount; git rename-detection pairs the
identical-content files at commit time.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/document-navigator/docs/media/video/README.md

@@ -0,0 +1,14 @@
+# `video`
+
+Video encoding, decoding, and thumbnail generation.
+
+<!-- begin:auto-docs -->
+## Packages in `video`
+
+2 packages.
+
+| Package | Description |
+|---|---|
+| [`@suaveplan/video`](./video/README.md) | Universal video metadata extraction, magic-byte format detection, resolution math, transform-pipeline planning, and a fluent pipeline builder. Zero browser-onl… |
+| [`@suaveplan/video-thumbnails`](./video-thumbnails/README.md) | Video thumbnail extraction and sprite-sheet generation backed by an injectable `FfmpegRunner`. The default runner — `FluentFfmpegRunner` — wraps `fluent-ffmpeg… |
+<!-- end:auto-docs -->