Replace Xournal++ with Signed for signing PDFs (#14999)

Signed, Omacom's PDF signing app, takes Xournal++'s place in the base
install and the preinstall set, so Remove and Install Preinstalls cover
it too. A migration installs it on existing machines, unless their owner
has removed the preinstalls; Xournal++ stays on machines that already
have it. The Filling out PDFs chapter now walks through Signed, the GUIs
chapter introduces it, the setup tip points to it, and the unused
Xournal++ config is gone.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

bin/omarchy-install-preinstalls

@@ -15,7 +15,6 @@ if gum confirm "Are you sure you want to restore all preinstalled web apps, TUI
     aether \
     cliamp \
     libreoffice-fresh \
-    xournalpp \
     pinta \
     obsidian \
     moonlight-qt \
@@ -23,7 +22,8 @@ if gum confirm "Are you sure you want to restore all preinstalled web apps, TUI
     monologue \
     omacalc \
     omawrite \
-    hype; then
+    hype \
+    signed; then
     echo -e "\nPreinstalls are still marked as removed. Fix the errors above and try again."
     exit 1
   fi

bin/omarchy-provision-owner

@@ -187,7 +187,7 @@ tips=(
   "Super + Space opens the Omarchy menu for apps, settings, and more"
   "Super + K shows all the key bindings"
   "Super is the Windows or command key on your keyboard"
-  "Use Xournal++ to sign PDFs"
+  "Sign PDFs and fill them in with Signed"
   "Share files with phones and laptops using LocalSend"
   "Turn any website into an app with Install > Web App in the menu"
   "Super + Return opens a terminal, Super + Shift + Return the browser"

bin/omarchy-remove-preinstalls

@@ -34,7 +34,6 @@ if gum confirm "Are you sure you want to remove all preinstalled web apps, TUI w
     aether \
     cliamp \
     libreoffice-fresh \
-    xournalpp \
     pinta \
     obsidian \
     moonlight-qt \
@@ -42,5 +41,6 @@ if gum confirm "Are you sure you want to remove all preinstalled web apps, TUI w
     monologue \
     omacalc \
     omawrite \
-    hype
+    hype \
+    signed
 fi