Built-in Node renderers

Import these from slackmark-node/renderers.

MermaidRenderer

Field	Default	Effect
`theme`	`"default"`	Mermaid theme
`backgroundColor`	`"white"`	PNG background
`deviceScaleFactor`	`2`	Screenshot pixel density
`maxSourceChars`	`50000`	Source limit
`maxEdges`	`500`	Graph complexity limit
`maxOutputBytes`	`10 MiB`	PNG byte limit
`maxWidth`, `maxHeight`	`4096`	Output pixels

Identity: "mermaid". Language: mermaid. Successful result: PNG bytes.

The renderer uses strict Mermaid security, fixed secure keys, local bundle bytes, CSP, request denial, and pre-screenshot dimension checks.

KatexRenderer

Field	Default	Effect
`backgroundColor`	`"white"`	PNG background
`deviceScaleFactor`	`2`	Screenshot pixel density
`fontSizePx`	`20`	Formula font size
`paddingPx`	`16`	PNG padding
`maxExpand`	`1000`	Macro expansion bound
`maxSize`	`50`	KaTeX element-size bound
`maxSourceChars`	`20000`	Source limit
`maxOutputBytes`	`10 MiB`	PNG byte limit
`maxWidth`, `maxHeight`	`4096`	Output pixels

Identity: "katex". Languages: math, katex, latex, tex. Successful result: PNG bytes.

KaTeX JavaScript, CSS, and fonts load from installed package bytes. Parsing and layout run inside the cancellable browser context with trust: false.

Both renderers receive source metadata in RenderRequest and cancellation/deadline state separately in the internal OperationContext argument. Both declare output: "bytes".