Add desktop app service and VM dev session tooling

Introduces a new `core/applications` QML/C++ module (`Nebula.Applications`) to discover `.desktop` entries, expose filterable application models, and launch installed apps safely from the shell. The desktop launcher now uses real installed apps with themed icon loading and fallback glyphs, adds output-aware surface sizing via `OutputTracker`, and wires in image/icon providers. It also adds VMware-focused Sway/shell wrapper scripts, updates Sway config/session env defaults, and refreshes README docs to document the new development flow and Desktop 0.1 behavior.

compositor/sway/dev/run-nebula-vm.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+# Convenience wrapper; the canonical VMware nebula-shell launcher is
+# scripts/run-nebula-vm.sh
+script_dir=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+exec /bin/sh "${script_dir}/../../../scripts/run-nebula-vm.sh" "$@"

compositor/sway/dev/run-sway-vm.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+# Recommended VMware development session entry point.
+#
+# Sets compositor-side development environment (cursor theme, software
+# cursors if needed) and starts Sway with the Nebula development config.
+# Sway then autostarts nebula-shell via scripts/run-nebula-vm.sh.
+#
+# Usage:
+#   ./compositor/sway/dev/run-sway-vm.sh
+#
+# Equivalent:
+#   export XCURSOR_THEME=Adwaita XCURSOR_SIZE=24
+#   sway -c compositor/sway/nebula-sway.conf
+#
+# Skip shell autostart:
+#   NEBULA_SHELL_AUTOSTART=0 ./compositor/sway/dev/run-sway-vm.sh
+
+set -eu
+
+script_dir=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+repo_root=$(CDPATH= cd -- "${script_dir}/../../.." && pwd)
+config="${repo_root}/compositor/sway/nebula-sway.conf"
+
+export XDG_CURRENT_DESKTOP="${XDG_CURRENT_DESKTOP:-NebulaOS}"
+export XDG_SESSION_DESKTOP="${XDG_SESSION_DESKTOP:-nebula}"
+export XCURSOR_THEME="${XCURSOR_THEME:-Adwaita}"
+export XCURSOR_SIZE="${XCURSOR_SIZE:-24}"
+
+# VMware often needs software cursors. This is development-specific.
+export WLR_NO_HARDWARE_CURSORS="${WLR_NO_HARDWARE_CURSORS:-1}"
+
+if [ ! -f "${config}" ]; then
+    echo "nebula: missing Sway config at ${config}" >&2
+    exit 1
+fi
+
+cd "${repo_root}"
+echo "nebula: starting Sway with ${config}"
+exec sway -c "${config}" "$@"

compositor/sway/nebula-sway.conf

@@ -2,17 +2,53 @@ set $mod Mod4
 set $term foot
 
 # NebulaOS temporary development compositor configuration
+#
+# Sway is invisible infrastructure. Nebula Desktop is the visible shell.
+# Do NOT add a bar block; Nebula provides its own top bar.
 
-# No Sway wallpaper or UI
+# -----------------------------------------------------------------------------
+# Output / resolution
+# -----------------------------------------------------------------------------
+# Development default: 1:1 scale, fill the current VMware display.
+# Request 1920x1080 when the output advertises that mode. If the mode is not
+# available, Sway keeps the output's preferred mode instead of failing.
+#
+# This is a development convenience, not a production architecture requirement.
+# Inspect modes:  swaymsg -t get_outputs
+# Force another mode (example):  swaymsg output <name> mode 1600x900
+output * scale 1
+output * mode 1920x1080
 output * bg #000000 solid_color
 
-# Development terminal
+# -----------------------------------------------------------------------------
+# Cursor
+# -----------------------------------------------------------------------------
+# The compositor owns the pointer cursor, not QML.
+# A branded Nebula cursor theme is a later task.
+seat * xcursor_theme Adwaita 24
+# If the cursor is invisible in VMware, start Sway with:
+#   WLR_NO_HARDWARE_CURSORS=1 sway -c compositor/sway/nebula-sway.conf
+# compositor/sway/dev/run-sway-vm.sh sets that automatically.
+
+# -----------------------------------------------------------------------------
+# Nebula shell autostart
+# -----------------------------------------------------------------------------
+# Starts nebula-shell through the VMware development wrapper, which sets
+# QT_QUICK_BACKEND=software. Production sessions must start nebula-shell
+# without that variable.
+#
+# Disable autostart for debugging:
+#   NEBULA_SHELL_AUTOSTART=0 sway -c compositor/sway/nebula-sway.conf
+#
+# Run from the repository root so this relative path resolves, or use
+# compositor/sway/dev/run-sway-vm.sh which does that for you.
+exec /bin/sh scripts/run-nebula-vm.sh
+
+# -----------------------------------------------------------------------------
+# Emergency development shortcuts (not the normal UX)
+# -----------------------------------------------------------------------------
 bindsym $mod+Return exec $term
-
-# Exit compositor
 bindsym $mod+Shift+e exec swaymsg exit
-
-# Reload configuration
 bindsym $mod+Shift+c reload
 
 # Remove Sway window decorations
@@ -21,6 +57,3 @@ default_floating_border pixel 0
 
 # Basic floating controls for development
 floating_modifier $mod normal
-
-# Do NOT add a bar block.
-# Nebula provides its own top bar.