tanin-icons: accent-reactive folder icon theme (replaces Papirus)

New package packaging/tanin-icons/ generating 5 thin themes Tanin-<accent>
that inherit Adwaita and recolour only the folder/place ramp to the muted
Fuji accent (HSL shift keeping per-stop lightness; 16px rasterised so the
size-exact inherited blue PNG can't win).

- style.py: _set_gsettings now also sets icon-theme=Tanin-<accent_key> so
  folders recolour live with the accent.
- desktop.py: hide Tanin-* from the manual icon picker (accent-driven, a
  manual pick would be overridden on the next accent change).
- panel.py: pin-add icon hint Papirus -> Adwaita.
- build/finish-tanin-repo.sh: tanin-icons in OWN_SIMPLE; AUR rebuilds add
  librewolf-bin, arch-update, timeshift-autosnap, xdg-terminal-exec, paru.
- camel.toml: icon_theme=Tanin-<accent>, icons=[adwaita], tanin-icons own
  package + the new rebuilt_aur entries.

Deliberately excludes unrelated in-flight work (calendar/gtklock/
online-accounts/overview-backdrop) still uncommitted in the tree.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packaging/tanin-icons/tanin-icons.install

@@ -0,0 +1,9 @@
+# Refresh the icon caches so GTK picks up the Tanin-<accent> themes.
+_themes() {
+  for t in ume shinkai take chikyu beni; do
+    gtk-update-icon-cache -qtf "/usr/share/icons/Tanin-$t" 2>/dev/null || true
+  done
+}
+
+post_install() { _themes; }
+post_upgrade() { _themes; }