Nested Schema Validation & Type mismatch check

[AbhinRustagi]

What

Closes TH-2076

Add schema-based type/enum validation for component props during materialization. Previously, the materializer only checked for missing required fields and unknown components. Values passed to a component were never validated against the declared JSON Schema type. This fills that gap.

Changes

• types.ts: Add ScalarParamType union ("string" | "number" | "boolean") and a schema?: unknown field on ParamDef to carry the raw JSON Schema fragment per parameter. Add "type-mismatch" to ValidationErrorCode.
• parser.ts: Populate param.schema from the compiled schema during compileSchema, so every ParamDef carries its full JSON Schema fragment.
• materialize.ts:
  • Introduce validateSchemaValue — a recursive JSON Schema validator that handles type: object (required keys, declared properties), type: array (single-schema items), and scalar leaf types/enums. Skips composite shapes ($ref, anyOf, oneOf, allOf), runtime AST nodes, and child ElementNodes (those validate as their own elements).
  • Add describeTypeMismatch and getScalarTypeInfo as scalar-leaf helpers.
  • Call validateSchemaValue for each positional argument after it's materialized, when the param carries a schema.
  • Extract pushValidationError helper to stop repeating statementId: ctx.currentStatementId at every call site.

Test Plan

• Verified locally

Checklist

• I linked a related issue, if applicable
• I updated docs/README when needed
• I considered backwards compatibility