Add desktop autostart and more applications

- stages/09-desktop.sh: new autostart section — copies .desktop files
  for Firefox, Ghostty, Nextcloud, Obsidian, Thunderbird into
  ~/.config/autostart/ so they launch at login
- stages/12-other-apps.sh: add Thunderbird, VirtualBox (Fedora via
  RPM Fusion), Zoom (via Flatpak); fallback Signal to Flatpak
  (no official RPM repo); remove FreeRDP (not needed on Fedora)

stages/12-other-apps.sh

@@ -13,8 +13,14 @@ pkg_install google-chrome-stable 2>/dev/null && ok "Chrome installed." \
 
 # ---- Signal Desktop ----
 info "Installing Signal Desktop..."
-pkg_install signal-desktop 2>/dev/null && ok "Signal installed." \
-  || warn "Signal not available. Check repo in stage 01."
+if pkg_install signal-desktop 2>/dev/null; then
+  ok "Signal installed via DNF."
+elif command -v flatpak &>/dev/null; then
+  flatpak install -y flathub org.signal.Signal 2>/dev/null && ok "Signal installed via Flatpak." \
+    || warn "Signal Flatpak failed. Install from https://signal.org/download/"
+else
+  warn "Signal not installed. Install from https://signal.org/download/"
+fi
 
 # ---- Zotero (reference manager) ----
 info "Installing Zotero..."
@@ -48,11 +54,32 @@ else
     warn "Nextcloud client not available."
 fi
 
-# ---- FreeRDP (for WinBoat RDP) ----
-info "Installing FreeRDP (Flatpak)..."
-if command -v flatpak &>/dev/null; then
-  flatpak install -y flathub com.freerdp.FreeRDP 2>/dev/null && ok "FreeRDP installed." \
-    || warn "FreeRDP Flatpak failed."
+# ---- Thunderbird (email client) ----
+info "Installing Thunderbird..."
+pkg_install thunderbird 2>/dev/null && ok "Thunderbird installed." \
+  || warn "Thunderbird not available."
+
+# ---- Oracle VirtualBox (VM manager) ----
+info "Installing VirtualBox..."
+if [ "$DISTRO_FAMILY" = "fedora" ]; then
+  # Available from RPM Fusion free
+  pkg_install VirtualBox 2>/dev/null && ok "VirtualBox installed." \
+    || warn "VirtualBox not available. Enable RPM Fusion free in stage 01."
+else
+  warn "VirtualBox not available on Debian via this script. Install manually."
+fi
+
+# ---- Zoom (video conferencing) ----
+info "Installing Zoom..."
+# The zoom wrapper script (~/.local/bin/zoom) is deployed in stage 06.
+# The actual Zoom app is best installed via Flatpak.
+if command -v zoom &>/dev/null && ! grep -q "wrapper" "$(which zoom)" 2>/dev/null; then
+  ok "Zoom already installed."
+elif command -v flatpak &>/dev/null; then
+  flatpak install -y flathub us.zoom.Zoom 2>/dev/null && ok "Zoom installed via Flatpak." \
+    || warn "Zoom Flatpak failed. Download from https://zoom.us/download"
+else
+  warn "Zoom not installed. Download from https://zoom.us/download"
 fi
 
 ok "Stage 12 complete: additional applications installed."