Add the Perplexity desktop app to Install > AI

Follows the T3 Code / Grok Bot flow: the Install > AI entry runs
omarchy-install-and-launch, so picking it installs the perplexity
package on demand and launches the app when the install finishes.
Remove > AI drops the package along with the app's own config, flags
file, and rpc-server runtime cache, keeping the perplexity-* caches
that belong to Perplexity's other products. Like the Hermes remover,
it sets -u so an unset HOME is a refusal rather than rm -rf paths
rooted at /.

The menu mark is a new U+E90B glyph in the Omarchy icon font, so it
reaches desktops through the next omarchy-settings release.

Co-Authored-By: Fable 5 <noreply@anthropic.com>
Co-Authored-By: Codex XHigh <noreply@openai.com>

default/fonts/omarchy/README.md

@@ -13,7 +13,8 @@ The private-use glyphs in `omarchy.ttf` are:
 - `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, 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
-- `U+E90C` — OpenClaw, traced from the lobster mascot the openclaw package ships as `dist/control-ui/favicon.svg`, since upstream publishes no monochrome SVG; `E90B` is left for the Perplexity mark already in flight on another branch
+- `U+E90B` — Perplexity, from <https://simpleicons.org/icons/perplexity.svg>
+- `U+E90C` — OpenClaw, traced from the lobster mascot the openclaw package ships as `dist/control-ui/favicon.svg`, since upstream publishes no monochrome SVG
 
 The agent marks are monochrome so the menu can render them using the active
 theme's foreground and selection colors.