Major rewrite of the README for Ghost.NativeWrapperGen:
- Clarifies project purpose, design, and intended usage.
- Adds concrete code examples of generated wrappers.
- Updates CLI usage and provides validated command lines.
- Replaces old config schema docs with detailed tables for all config fields, including new `remaps` and `actions`.
- Documents the new config-driven routing and remapping system.
- Explains the action-based method routing with conditions and apply steps.
- Details naming conventions and method name derivation.
- Provides a full, modern config example for nvtt.
- Updates recommended workflow for wrapper regeneration and build.
- Emphasizes the design principle of keeping policy in config.
- Removes outdated sections and limitations.
- Improves formatting and accessibility for new users.
