feat: add bump-version.sh script for version management

Automates version bumps across all version source files:
- Cargo.toml (PRIMARY - workspace.package.version)
- debian/changelog (prepend new entry)
- debian/control (update Version field)
- scripts/build-package.sh (update VERSION variable)
- frontend/package.json (update version field)
- Stale references check after bump

Usage: ./scripts/bump-version.sh <new_version> <old_version>

debian/prerm

@@ -0,0 +1,20 @@
+#!/bin/bash
+set -e
+
+case "$1" in
+    remove|upgrade|deconfigure)
+        # Stop services gracefully
+        if systemctl is-active --quiet patch-manager.target 2>/dev/null; then
+            systemctl stop patch-manager.target 2>/dev/null || true
+        fi
+        ;;
+
+    failed-upgrade)
+        ;;
+
+    *)
+        echo "prerm called with unknown argument \`$1'" >&2
+        ;;
+esac
+
+exit 0