chore: Add Copilot instructions for repository

.github/copilot-instructions.md

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+# Copilot Instructions for Riven
+
+## Project Overview
+
+Riven is a Rust library for the [Riot Games API](https://developer.riotgames.com/). The project's goals are **speed**, **reliability**, and **maintainability**. Riven handles rate limits and large requests with ease, providing an asynchronous, thread-safe interface for interacting with the Riot API.
+
+Key features:
+- Fast, asynchronous, thread-safe API client
+- Automatic retry logic for failed requests
+- Support for all Riot API endpoints
+- Auto-generated data structures from Riot API schema
+- WebAssembly (Wasm) compilation support
+- Strictly forbids unsafe code
+
+## Project Structure
+
+This is a Cargo workspace with the following structure:
+
+- **`riven/`** - Main Rust library crate
+  - `src/` - Hand-written and generated Rust source code
+  - `srcgen/` - NodeJS code generator using doT.js templates
+  - `tests/` - Integration tests
+  - `examples/` - Example code (e.g., proxy example)
+- **`.github/workflows/`** - CI/CD workflows (CI, publish)
+- **Root scripts** - `test.bash`, `test-full.bash`, `test-min-deps.bash`, `test-wasm.bash`, `doc.bash`
+
+## Code Generation
+
+The project uses **NodeJS** to generate Rust code from the Riot API schema:
+- Code generation is in `riven/srcgen/`
+- Templates use [doT.js](https://olado.github.io/doT/index.html)
+- Run code generation: `node riven/srcgen` from repository root
+- Requires NodeJS and dependencies installed via `npm ci` in `riven/srcgen/`
+
+## Development Workflow
+
+### Prerequisites
+
+1. **Rust** - MSRV is 1.71.1 (specified in `riven/Cargo.toml`)
+2. **API Key** - Place Riot API key in `RGAPI_KEY` environment variable or `apikey.txt` file for testing
+3. **NodeJS** - Required for code generation (srcgen)
+
+### Building
+
+```bash
+# Standard build
+cargo build
+
+# Build with all features
+cargo build --all-features
+
+# Build with nightly features
+cargo build --features riven/nightly,riven/deny-unknown,riven/eserde,riven/__proxy
+```
+
+### Testing
+
+```bash
+# Run tests (requires RGAPI_KEY)
+cargo test --features riven/nightly,riven/tracing,riven/eserde,riven/deny-unknown
+
+# Run tests with script
+./test.bash
+
+# Test WebAssembly compilation
+wasm-pack test --node -- --features nightly,deny-unknown,eserde
+```
+
+**Important**: Tests require a valid Riot API key in `RGAPI_KEY` environment variable or `apikey.txt` file.
+
+### Linting and Formatting
+
+```bash
+# Format code
+cargo fmt --all
+
+# Check formatting
+cargo fmt --all -- --check
+
+# Run Clippy
+cargo clippy --all-features --all-targets -- -D warnings
+```
+
+**Formatting configuration** is in `rustfmt.toml` with specific settings like:
+- `group_imports = "StdExternalCrate"`
+- `imports_granularity = "Module"`
+- `use_field_init_shorthand = true`
+
+## Code Standards
+
+1. **No unsafe code** - The project uses `#![forbid(unsafe_code)]`
+2. **Follow rustfmt configuration** - Use the settings in `rustfmt.toml`
+3. **Pass Clippy with warnings as errors** - All code must pass Clippy checks
+4. **Maintain MSRV compatibility** - Code must compile on Rust 1.71.1+
+5. **Use async/await** - The library is fully asynchronous using Tokio (or gloo-timers for Wasm)
+6. **Thread-safe design** - All code should be thread-safe
+
+## Feature Flags
+
+When writing code, be aware of these feature flags:
+
+- **`nightly`** - Enables nightly-only optimizations (parking_lot)
+- **`default-tls`** / **`native-tls`** / **`rustls-tls`** - TLS backend selection
+- **`tracing`** - Use tracing instead of log for diagnostics
+- **`metrics`** - Enable metrics collection
+- **`eserde`** - Enhanced serde support
+- **`deny-unknown`** - Error on unknown fields/enum variants (useful for strict validation)
+- **`__proxy`** - Required for proxy example
+
+## Testing Guidelines
+
+1. **Integration tests** are in `riven/tests/`
+2. Tests require a valid Riot API key
+3. Use appropriate feature flags when testing:
+   - `nightly` for nightly features
+   - `tracing` for span-based logging
+   - `deny-unknown` for strict validation
+   - `eserde` for enhanced serialization
+4. **Wasm tests** must be run with `wasm-pack`
+5. Tests should handle rate limits and API errors gracefully
+
+## CI/CD
+
+The project uses GitHub Actions with these workflows:
+
+- **CI** (`ci.yml`) - Runs on push, PR, and daily schedule
+  - Checks code with stable and nightly Rust
+  - Runs tests with multiple feature combinations
+  - Runs lints (fmt, clippy)
+  - Builds documentation
+  - Verifies MSRV
+  - Tests Wasm compilation
+- **Publish** (`publish.yml`) - Publishes to crates.io
+
+## Documentation
+
+- **Main docs**: https://docs.rs/riven/
+- **API reference**: Auto-generated from code
+- Build documentation locally: `cargo doc --features nightly` (or use `./doc.bash`)
+- CI builds with `cargo docs-rs -p riven` (requires cargo-docs-rs tool)
+- Doc warnings are treated as errors in CI
+
+## Dependencies and Versioning
+
+- **Semantic versioning** - With caveats due to Riot API changes
+- **Breaking changes** in models/endpoints increment MINOR version (not MAJOR)
+- Keep dependencies up-to-date but maintain MSRV compatibility
+- Key dependencies: `reqwest`, `serde`, `tokio`, `parking_lot`
+
+## Common Tasks
+
+### Adding a new endpoint or model
+1. Update `riven/srcgen/` templates if needed
+2. Run `node riven/srcgen` to regenerate code
+3. Test with appropriate feature flags
+4. Ensure code passes fmt and clippy
+
+### Fixing a bug
+1. Write a test that reproduces the issue
+2. Make minimal changes to fix
+3. Verify fix with tests
+4. Ensure no clippy warnings
+
+### Updating dependencies
+1. Check MSRV compatibility
+2. Update `Cargo.toml`
+3. Run full test suite
+4. Verify Wasm compilation still works
+
+## Best Practices
+
+1. **Minimize external dependencies** - Only add when truly necessary
+2. **Write async code** - Use async/await, avoid blocking
+3. **Handle errors properly** - Return `Result<T>` or `Result<Option<T>>`
+4. **Document public APIs** - All public items should have doc comments
+5. **Test edge cases** - Especially API errors, rate limits, missing data
+6. **Consider Wasm compatibility** - Avoid platform-specific code without cfg gates
+7. **Use type safety** - Leverage Rust's type system for correctness
+8. **Follow existing patterns** - Match the style of existing code
+
+## Getting Help
+
+- Review existing code in `riven/src/` for patterns
+- Check tests in `riven/tests/` for usage examples
+- Refer to Riot API documentation: https://developer.riotgames.com/
+- Check issues: https://github.com/MingweiSamuel/Riven/issues