Generate Node config types from schema

[BYVoid]

Summary

• generate Node OpenCCConfig declaration types from data/config/opencc_config.schema.json
• replace the broad Record<string, unknown> config type with schema-derived config, segmentation, conversion, and dictionary unions
• add npm run generate:node-config-types for refreshing declarations
• add Bazel targets for generation and generated-output checking:
  • bazel run //scripts:generate_node_config_types
  • bazel test //scripts:generate_node_config_types_test

Tests

• node scripts/generate-node-opencc-config-types.js --check
• npm run generate:node-config-types
• bazel run //scripts:generate_node_config_types
• bazel test //scripts:generate_node_config_types_test
• TypeScript ESM/CJS smoke compile with npx -p typescript tsc
• npm test