feat: add raw schema and db properties to FieldMeta

[brainkim]

Summary

• Add schema and db properties to FieldMeta for direct access to raw data
• Mark existing cooked properties as deprecated (but still working)

New API (preferred)

const fields = Users.fields();

fields.email.schema     // ZodType - use Zod APIs for introspection
fields.email.db         // FieldDBMeta - raw db metadata
fields.email.db.unique  // boolean
fields.email.db.autoIncrement

Old API (deprecated, still works)

fields.email.unique     // boolean
fields.email.type       // "email" 
fields.email.required   // boolean

Migration

Users can migrate gradually:

// Before
const isGenerated = field.autoIncrement || field.inserted;

// After
const isGenerated = field.db.autoIncrement || field.db.inserted;

Notes

• Additive and non-breaking
• Deprecated properties will be removed in a future major version
• Form-specific logic (type, required, etc.) will move to @b9g/forms

Related to #15

Test plan

• All 584 tests pass
• Type checking passes
• Manual verification of new API

🤖 Generated with Claude Code

[brainkim]

Too many cooks