Cover the remaining Zalo TextStyle palette the 2.1 release didn't use:
Red / Orange / Yellow / Green, Small (f_13), and Indent with indentSize.
### Colours via GFM admonitions
Markdown doesn't have native colour syntax, so reuse GFM admonitions — an
extension most LLMs already produce when asked for warnings/tips:
> [!TIP] → Green (c_15a85f)
> [!NOTE] → Yellow (c_f7b503)
> [!IMPORTANT] → Yellow (same as NOTE)
> [!WARNING] → Orange (c_f27806)
> [!CAUTION] → Red (c_db342e)
> [!DANGER] → Red (alias)
The marker line (`> [!TYPE]`) is stripped; the colour is applied to every
subsequent blockquote line until a non-blockquote line ends the block. Each
coloured line still gets the `│ ` quote prefix so the visual grouping stays
even when Zalo strips styles in older clients.
### Small font
`<small>text</small>` → TextStyle.Small (f_13) inline span. HTML-like tag
avoids collision with any markdown syntax and LLMs produce it naturally for
footnote-sized content.
### Indent (nested lists)
A list item with leading whitespace gets a TextStyle.Indent span whose
`indentSize` is `Math.floor(leadingSpaces / 2)`. zca-js's handleStyles
encodes this as `ind_<N>0` (e.g. indentSize=2 → "ind_20") so Zalo client
shifts the line by the correct level. Only applies to ul/ol items; bare
indented paragraphs keep their literal whitespace.
Verified against 11 samples covering every block/inline path.