* refactor!: move shared primitives below dom-css and core
dom-css depended on core for color conversion, base64 helpers, text
direction, and web-font assets, so core could not use dom-css and every
caller special-cased HTML and Tailwind output.
Color conversion and management, base64 helpers, and text/layout
direction now live in scene-graph under `color`, `bytes`, and
`text-direction`. dom-css takes web-font resolution as an injected
`fonts` option and owns the font face types, so it depends only on
scene-graph and core can depend on it.
BREAKING CHANGE: `@open-pencil/core/color` and `@open-pencil/core/bytes`
are removed, and the direction helpers are no longer exported from
`@open-pencil/core/text`; import them from `@open-pencil/scene-graph`
subpaths. `exportHTMLBundle` takes a font resolver in `fonts` instead of
`'assets'`.
* fix(tools): import color parsing from scene-graph in visual bisect
* fix(mcp): declare the scene-graph dependency
MCP imports `@open-pencil/scene-graph/bytes` since base64 helpers moved
there, but only reached scene-graph through core, so isolated installs
and package checks depended on transitive resolution.
* refactor!: use js-base64 directly instead of a base64 wrapper
Base64 helpers had moved into scene-graph only to sit below dom-css,
but they are a thin wrapper over js-base64 and unrelated to the graph;
fig already called js-base64 directly.
Callers use js-base64 and check `isValid` where input comes from outside
(clipboard, imported HTML, tool arguments, the plugin API). A new
`open-pencil/no-hand-rolled-base64` lint rule rejects atob, btoa, and
Buffer Base64 conversions, and AGENTS.md records the convention.
BREAKING CHANGE: `@open-pencil/core/bytes` is removed; use `js-base64`.
* fix(dom-css): keep images with invalid Base64 inline in HTML export
`exportHTMLBundle` accepts documents parsed from outside HTML, and
js-base64 drops characters it cannot decode, so extracting an invalid
image data URL wrote different bytes. Such images now stay inline.
