Add MYPRIMETYPE and layout stats box

[mahithapen]

1. New datatype: MYPRIMETYPE

• Added MYPRIMETYPE to datatype maps so it is available in the editor/type selectors.
• Added validation logic for defaults:
  • accepts positive odd integers (1, 3, 5, 7, 9, 11, ...) per requested pattern.
• Integrated across DB maps to avoid export/import/check issues when switching dialects.

2. New Layout Stats Box

• Added StatsBox component to the editor canvas.
• Displays live layout/graph stats:
  • number of tables
  • number of relationships
  • total fields
  • average fields per table
  • max depth
  • max out-degree
  • connected components
  • isolated tables
  • bounding width / bounding height