New command: `grit generate suite` — scaffold whole management systems (school, ERP, CRM, hotel, hospital) in one shot

[MUKE-coder]

grit generate resource Post is great for one entity. Real management systems (School Management, ERP, CRM, Hospital, Hotel) have 30–50 related entities — generating each by hand is slow and the relationships have to be wired manually each time.

Across my Kits build plans, kits for School Management, CRM, ERP, and Marketplace each have 15–30 entities. The Grit code generator is fantastic per-entity but a whole afternoon to scaffold the suite.

Proposed fix:
New grit generate suite <yaml-or-builtin> command:

• Reads a YAML manifest of entities + relations + indices + admin pages
• Runs the existing grit generate resource for each entity in dependency order
• Wires the relations (belongs_to / has_many / many_to_many) automatically
• Ships built-in manifests for common suites: school, erp-lite, crm, hotel, hospital, pos, inventory
• Each builtin is a starting point — caller edits the YAML and re-runs to evolve the suite

Examples:
```
grit generate suite school # uses built-in manifest
grit generate suite ./my-suite.yaml # custom manifest
grit generate suite erp-lite --skip Payroll # generates ERP suite minus the payroll module
```

Sketches:
```yaml

school.yaml (built-in)

name: school
entities:

• AcademicYear: { year, startDate, endDate }
• Term: { yearId: belongs_to:AcademicYear, name, startDate, endDate }
• Class: { name, grade, classTeacherId: belongs_to:User }
• Student: { firstName, lastName, classId: belongs_to:Class }
• ...
  ```

This is the move that makes Grit "the way to scaffold any management system." Big differentiator from generic CRUD generators.