Add PrefixStrippingProvider interface and implement it in all providers
(EmbedFSProvider, LocalFSProvider, ZipFSProvider) to support serving
files from subdirectories at the root level.
Adds WithStripPrefix method to allow serving files from subdirectories
at the root path. For example, files at /dist/assets can be made
accessible via /assets by calling WithStripPrefix("/dist").
- Add ServersConfig and ServerInstanceConfig structs
- Support configuring multiple named server instances
- Add global timeout defaults with per-instance overrides
- Add TLS configuration options (SSL cert/key, self-signed, AutoTLS)
- Add validation for server configurations
- Add helper methods for applying defaults and getting default server
- Add conversion helper to avoid import cycles
