[schemas] Migrate model/component wire format to canonical camelCase (v1beta2/v1beta3)

[hortison]

Current Situation

The ModelDefinition.Registrant field in v1beta2/model references v1beta1/connection.Connection, which has snake_case JSON tags (created_at, user_id, deleted_at). This causes mesheryctl model generate output and server API responses to emit non-canonical wire format, violating the AGENTS.md contract:

"Wire is camelCase everywhere; DB is snake_case; the ORM layer is the sole translation boundary."

Similarly, ComponentDefinition.Model in both v1beta2 and v1beta3 component schemas references v1beta1/model.ModelDefinition (snake_case JSON tags: components_count, relationships_count). The ComponentSchemaVersion constant in v1beta3/const.go is also stale at "components.meshery.io/v1beta2" while both the YAML default and model init templates already emit v1beta3.

Proposed Change

1. v1beta2/model.ModelDefinition.Registrant → reference v1beta3/connection.Connection (camelCase JSON tags)
2. v1beta2/component.ComponentDefinition.Model → reference v1beta2/model.ModelDefinition
3. v1beta3/component.ComponentDefinition.Model → reference v1beta2/model.ModelDefinition
4. v1beta3/const.go#ComponentSchemaVersion → "components.meshery.io/v1beta3"

Acceptance Criteria

• mesheryctl model generate emits registrant.createdAt, registrant.userId (camelCase)
• mesheryctl model generate emits "schemaVersion": "components.meshery.io/v1beta3" in component files
• go build ./... passes across meshery/schemas, meshery/meshkit, and meshery/meshery
• No DB AutoMigrate changes required
• Consumer-audit CI gate passes

Related PRs

• meshery/meshkit PR: Registry bridge adapters
• meshery/meshery PR: Server handler + UI field name updates

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• 👨‍💻Models Repository

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• Contributing Models
  • Contributing Components
  • Contributing Relationships

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[github-actions]

This issue has been labeled with 'component/mesheryctl'. Note that after making changes you need to update it in the mesheryctl command tracker spreadsheet.

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