docs(obsidian-markdown): document 1.14 color highlights; add references/HIGHLIGHTS.md

What's missing

skills/obsidian-markdown/SKILL.md documents highlights in a single line, under a section that exists only to hold it:

## Obsidian-Specific Formatting

```markdown
==Highlighted text==                   Highlight syntax
```

As of Obsidian 1.14.0 (desktop, 2026-09-02, early access) highlights are no longer a one-liner — they carry a color, and the color is part of the Markdown, not a CSS class or a plugin.

From the 1.14.0 changelog:

Added color highlights. Add a color emoji (, , , , ) to the start of a highlight to change its color, or pick a color from the new formatting submenu.

Typing == in the editor now suggests highlight colors.

Live Preview: When the cursor overlaps a highlight, an inline swatch now appears. Click it to quickly change the highlight color.

Why this one matters for an agent

The color lives inside the delimiters, so an agent that doesn't know the convention gets it wrong in two different ways:

• Authoring — reaching for ==<span style="color:red">text</span>== or a cssclasses hack, when a plain emoji prefix is the supported syntax.
• Round-tripping — an agent editing a note that already contains == blocker== may "clean up" what looks like a decorative emoji and silently drop the highlight's color. Same for reflowing text: moving the emoji after the first word turns a red highlight into a yellow highlight that happens to contain an emoji.

There's also no authoritative page to fall back on. help.obsidian.md/syntax still lists only | Highlight | == == | ==Highlighted text== |, with no mention of colors — so the changelog is currently the only source, which is exactly the gap this repo exists to close.

Proposed change

Replace the ## Obsidian-Specific Formatting catch-all with a real ## Highlights section, and add references/HIGHLIGHTS.md alongside the existing CALLOUTS.md / EMBEDS.md / PROPERTIES.md — same pattern as those: a short table in SKILL.md, details in the reference.

In SKILL.md

## Highlights

```markdown
==Highlighted text==                   Default (yellow)
== Highlighted text==                Colored highlight
```

A color emoji at the **start of the highlight text** sets its color (Obsidian 1.14+):
`` red, `` orange, `` green, `` blue, `` purple. The emoji is the syntax, not
decoration — do not strip or reposition it when editing an existing highlight.

See [HIGHLIGHTS.md](references/HIGHLIGHTS.md) for the color table, nesting, and editor behavior.

In references/HIGHLIGHTS.md

• The five supported colors, one row each, with exact syntax.
• The default (no emoji) case, and that an unsupported emoji is not a color — it stays literal text inside a yellow highlight.
• Editing rules for agents: preserve a leading color emoji verbatim; it must come first; only one per highlight.
• Interaction with other inline syntax — highlights wrapping bold/italic/wikilinks, and highlights inside callouts and table cells.
• Editor affordances that don't change the Markdown but explain what users see: the == color suggester and the Live Preview swatch.
• A note that the colors carry no meaning in Obsidian itself — the mapping is the user's convention, so an agent should follow whatever mapping a vault already uses rather than inventing one.

Notes

• Worth a mention in the ## Complete Example at the bottom too, which currently uses a plain ==January 30th==.
• I've only verified the desktop 1.14.0 changelog and the current state of the help docs — happy to hold if the syntax is still moving in early access.
• Glad to open a PR with the section and the reference file if the shape above looks right.