feat: add OpenAPI and Smithy model gateway target types

[tejaskash]

Summary

• Add openApiSchema and smithyModel as new gateway target types, enabling users to auto-derive tools from an OpenAPI JSON spec or Smithy JSON model
• Add --schema flag (accepts local .json file path or s3:// URI) and --schema-s3-account flag for cross-account S3 access
• Add SchemaSourceSchema Zod type, SchemaBasedTargetConfig discriminated union variant, createSchemaBasedGatewayTarget() primitive method, and CLI validation

Changes

• Schema (src/schema/schemas/mcp.ts): SchemaSourceSchema (inline/S3), schemaSource field on AgentCoreGatewayTargetSchema, superRefine rules
• CLI validation (src/cli/commands/add/validate.ts): JSON-only enforcement, file existence check, S3 URI format validation
• CLI primitive (src/cli/primitives/GatewayTargetPrimitive.ts): --schema/--schema-s3-account flags, createSchemaBasedGatewayTarget() method
• TUI types (src/cli/tui/screens/mcp/types.ts): SchemaBasedTargetConfig in discriminated union, new TARGET_TYPE_OPTIONS
• TUI flow (AddGatewayTargetFlow.tsx): Branch for schema-based targets
• Tests: 15 schema tests, 3 discriminated union tests, 17 integration tests (lifecycle, S3, cross-account, validation)

Usage

# OpenAPI (local file)
agentcore add gateway-target --name petstore --type open-api-schema \
  --schema ./specs/petstore.json --gateway my-gw

# Smithy (S3 URI)
agentcore add gateway-target --name my-svc --type smithy-model \
  --schema s3://my-bucket/models/service.json --gateway my-gw

# Cross-account S3
agentcore add gateway-target --name petstore --type open-api-schema \
  --schema s3://my-bucket/specs/petstore.json --schema-s3-account 123456789012 --gateway my-gw

Test plan

• Schema unit tests pass (SchemaSourceSchema validation, AgentCoreGatewayTargetSchema superRefine)
• Discriminated union type narrowing tests pass
• Integration tests pass (OpenAPI local file, S3 URI, cross-account, Smithy, validation errors)
• TypeScript compiles cleanly
• Pre-commit hooks (eslint, prettier, secretlint) pass

Related

• CDK PR: aws/agentcore-l3-cdk-constructs (feat/openapi-smithy-targets)

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	42.61%	3739 / 8774
🔵	Statements	42.2%	3944 / 9345
🔵	Functions	44.27%	738 / 1667
🔵	Branches	44.45%	2443 / 5495

Generated in workflow #909 for commit d9101fe by the Vitest Coverage Report Action

[aidandaly24]

two nit comments but other than that I think this looks clean and good to me.

[aidandaly24]

thanks for making the updates approved