Implement the Ollama DELETE /api/delete endpoint for removing models
from the server.
- Add DeleteRequest type with model field in src/types/delete.rs
- Add OllamaClient::delete() async method in src/lib.rs
- Register delete module in src/types/mod.rs
- Add usage example in examples/delete.rs
- Add crate-level docs with usage examples for lib.rs
- Document OllamaClient, OllamaClientBuilder, and all public methods
- Document error module with OllamaError variants and OllamaResult
- Document types module with endpoint mapping table
- Document all types in common, chat, generate, ps, pull, tags, version
- Add doc examples for builders, constructors, and key types
- All 26 doc-tests pass
