Add TypeScript support and improve project configuration for opencc-wasm

[frankslin]

This commit enhances the opencc-wasm library with TypeScript support and
implements a cleaner build architecture with semantic separation between
intermediate build artifacts and publishable distribution.

TypeScript Support:

• Add comprehensive type definitions (index.d.ts) with full JSDoc documentation
• Define interfaces: ConverterOptions, ConverterFunction, OpenCCNamespace, etc.
• Provide complete type safety for better IDE support and developer experience

Build Architecture Redesign (semantic separation):

• build/ - Intermediate WASM artifacts (gitignored, for tests/development)
  • build/opencc-wasm.esm.js - ESM WASM glue
  • build/opencc-wasm.cjs - CJS WASM glue
  • build/opencc-wasm.wasm - WASM binary
• dist/ - Publishable distribution (committed, for npm)
  • dist/esm/ - ESM package entry
  • dist/cjs/ - CJS package entry
  • dist/data/ - OpenCC config and dictionary files

Invariants and Semantics:

• Tests import source (index.js) → loads from build/
• Published package exports dist/ only
• build/ = internal intermediate artifacts
• dist/ = publishable artifacts
• Clear separation ensures tests validate actual build output

Enhanced .gitignore:

• Add build/ to gitignore (intermediate artifacts)
• Add node_modules/, logs, OS-specific files (.DS_Store, Thumbs.db)
• Exclude editor configurations (.vscode/, .idea/)
• Add cache and temporary file exclusions

Two-Stage Build Process:
Stage 1 (build.sh):

• Compiles C++ to WASM using Emscripten
• Outputs to build/ directory

Stage 2 (build-api.js):

• Copies WASM artifacts from build/ to dist/
• Transforms source paths for production
• Generates API wrappers for ESM and CJS
• Copies data files

Package Configuration (package.json):

• Add "types" field pointing to index.d.ts
• Update "main" and "module" to point to API wrappers in dist/
• Add comprehensive "exports" map:
  • "." - Main API (ESM/CJS wrappers)
  • "./wasm" - Direct access to WASM glue for advanced users
  • "./dist/*" - Wildcard for flexible file access
• Include LICENSE and NOTICE in published files

Documentation:

• Add comprehensive README section explaining build architecture
• Document project structure with invariants
• Explain semantic separation between build/ and dist/

Benefits:

• Better TypeScript integration and IDE autocomplete
• Cleaner, more maintainable directory structure
• Tests validate actual build output, not stale dist files
• Clear semantic separation between internal and publishable artifacts
• Professional project setup following modern npm best practices
• Long-term maintainability through clear invariants

[Copilot]

Pull request overview

This PR adds comprehensive TypeScript support and improves the project configuration for the opencc-wasm library. The changes include type definitions, enhanced gitignore patterns, and updated package.json to properly reference the new TypeScript types and build outputs.

• Added complete TypeScript type definitions with JSDoc documentation
• Updated package.json to reference new ESM/CJS build locations and include TypeScript types
• Enhanced .gitignore with comprehensive exclusions for node_modules, logs, OS files, and editor configurations

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
wasm-lib/package.json	Updated module entry points to new dist/esm and dist/cjs paths, added TypeScript types field, and included LICENSE/NOTICE in published files
wasm-lib/index.d.ts	New TypeScript type definitions file providing complete type safety with interfaces for ConverterOptions, ConverterFunction, OpenCCNamespace, and related types with JSDoc examples
wasm-lib/.gitignore	Expanded from single line to comprehensive exclusions covering node_modules, logs, OS files, editor configs, and cache directories

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 9 changed files in this pull request and generated 1 comment.

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[Copilot]

The generated dist files (opencc-wasm.js and opencc-wasm.cjs) are minified production bundles that should not be committed to git as they are binary-like artifacts that create merge conflicts and bloat the repository. According to the PR description, build/ is gitignored for intermediate artifacts, but dist/ should contain publishable outputs. However, these specific Emscripten-generated WASM glue files are large minified files (likely auto-generated) that should be treated as build outputs.

Consider either:

1. Adding dist/esm/opencc-wasm.js and dist/cjs/opencc-wasm.cjs to .gitignore (they can be generated during npm prepare/publish hooks)
2. If they must be committed, document why in the README

Suggested change

	# Dist outputs (keep in git for npm package)
	# Dist outputs (keep in git for npm package)
	# (except specific Emscripten-generated WASM glue files)
	dist/esm/opencc-wasm.js
	dist/cjs/opencc-wasm.cjs