feat: improve mo purge UX with pagination and smart project detection

- Add pagination for project list based on terminal height
- Show position indicator [5/25] when scrolling
- Fix GB display for values < 1 (0.6GB instead of .6GB)
- Improve project name detection by walking up to find project root
- Change default editor from nano to vim

lib/manage/purge_paths.sh

@@ -92,7 +92,7 @@ manage_purge_paths() {
     echo ""
 
     # Open in editor
-    local editor="${EDITOR:-${VISUAL:-nano}}"
+    local editor="${EDITOR:-${VISUAL:-vim}}"
     echo -e "Opening in ${CYAN}$editor${NC}..."
     echo -e "${GRAY}Save and exit to apply changes. Leave empty to use defaults.${NC}"
     echo ""