Replace the cabinet's hand-written heroicons-style SVG icon components with
the Remnawave panel's own icon family — Phosphor via react-icons/pi (Duotone).
All icons now live in a single central barrel (src/components/icons:
index + extended-icons + editor-icons, 144 icons); every feature file imports
from it instead of redefining inline SVGs (~440 icon defs removed).
- Add react-icons dependency
- Desktop nav (AppShell) now uses the central Phosphor icons, removing a
stroke-vs-duotone inconsistency the partial migration introduced
- Icons with custom props (SortIcon's direction, expandable chevrons) kept as
thin Phosphor wrappers; the RemnawaveIcon brand logo and animated SVGs
(checkmarks, spinners) are intentionally left as-is
- Restore the original per-call-site icon sizes wherever the centralized
default differed (211 call sites)
