Give Hermes the mark that reads at menu size

U+E90A carried a trace of the Hermes app icon: a portrait whose detail collapses
into a grey smudge beside the ten flat silhouettes the rest of the font is made
of, which is what icon-font.md warns against when it says to pick a source whose
silhouette alone reads.

It is Font Awesome's staff-snake now, under CC BY 4.0 -- the mark Hermes serves
as its favicon and titles its README with. The README records that, along with
the licence the artwork carries, since it is the only note of where these come
from.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

default/fonts/omarchy/README.md

@@ -12,7 +12,7 @@ The private-use glyphs in `omarchy.ttf` are:
 - `U+E907` — Ollama, from <https://simpleicons.org/icons/ollama.svg>
 - `U+E908` — T3 Code, traced from the app icon in <https://aur.archlinux.org/cgit/aur.git/plain/t3code-icon.png?h=t3code-bin>, since upstream publishes no monochrome SVG
 - `U+E909` — Ori, from <https://openrouter.ai/brand/v2/openrouter-glyph-dark.svg>, OpenRouter's own mark: Ori ships no separate logo and its product page uses this one
-- `U+E90A` — Hermes, traced from the Hermes app icon (<https://hermes-agent.nousresearch.com/>), the same art the `hermes-desktop` package ships as its icon
+- `U+E90A` — Hermes, Font Awesome's staff-snake (CC BY 4.0) from <https://fontawesome.com/icons/staff-snake>, the mark Hermes serves as its favicon: their app icon is a portrait that reads as a smudge at menu size
 
 The agent marks are monochrome so the menu can render them using the active
 theme's foreground and selection colors.