interface: add custom proxy

[bdbai]

Fixes #41

[Copilot]

Pull request overview

Adds per-client custom proxy configuration across the public client API, interface options, backend implementations, and backend test fixtures.

Changes:

• Introduces CustomProxy and replaces the boolean default-proxy flag with ProxyOptions.
• Implements proxy handling for curl, reqwest, WinHTTP, NSURLSession, and no/custom handling for WinRT.
• Adds proxy backend tests and refactors shared Hyper test fixture setup.

Reviewed changes

Copilot reviewed 32 out of 33 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/client/proxy.rs	Adds public custom proxy builder type.
src/client/builder.rs	Adds custom_proxy and updates no_proxy.
src/client.rs	Exports CustomProxy.
README.md	Moves WinHTTP to completed MVP backends.
nyquest-interface/src/client/options.rs	Adds ProxyOptions to client configuration.
nyquest-interface/src/client.rs	Exports ProxyOptions.
nyquest-backend-tests/src/lib.rs	Refactors shared fixture server setup.
nyquest-backend-tests/src/hyper_fixture_collection.rs	Extracts reusable Hyper fixture collection.
nyquest-backend-tests/src/fixtures/client_options/proxy.rs	Adds proxy behavior tests.
nyquest-backend-tests/src/fixtures/client_options.rs	Registers proxy tests.
Cargo.lock	Updates platform dependency lock entries.
backends/winrt/src/response.rs	Moves stream reader state out of common response.
backends/winrt/src/client.rs	Adapts WinRT proxy option handling.
backends/winrt/src/blocking/timer_ext.rs	Updates Windows async blocking call.
backends/winrt/src/blocking.rs	Moves blocking reader state into blocking response.
backends/winrt/src/async/read_task.rs	Adds async read state machine.
backends/winrt/src/async.rs	Uses new WinRT async read task.
backends/winrt/Cargo.toml	Updates Windows crate versions.
backends/winhttp/src/session.rs	Passes proxy options to session creation.
backends/winhttp/src/handle/session.rs	Adds WinHTTP proxy option mapping.
backends/winhttp/src/async/threadpool.rs	Removes custom threadpool helper.
backends/winhttp/src/async/client.rs	Uses windows-threading for async setup work.
backends/winhttp/src/async.rs	Removes deleted threadpool module.
backends/winhttp/Cargo.toml	Updates Windows dependencies and adds windows-threading.
backends/reqwest/src/client.rs	Adds reqwest proxy option mapping.
backends/nsurlsession/src/response.rs	Adjusts Objective-C API calls for updated bindings.
backends/nsurlsession/src/datatask/delegate.rs	Adjusts Objective-C API calls for updated bindings.
backends/nsurlsession/src/client.rs	Adds NSURLSession proxy dictionary support.
backends/nsurlsession/src/blocking.rs	Adjusts Objective-C API calls for updated bindings.
backends/nsurlsession/src/async.rs	Adjusts Objective-C API calls for updated bindings.
backends/nsurlsession/Cargo.toml	Updates Objective-C Foundation dependency/features.
backends/curl/src/request.rs	Adds curl proxy option setup.
backends/curl/src/curl_ng/easy/opt.rs	Adds curl proxy-related option wrappers.

Comments suppressed due to low confidence (2)

backends/reqwest/src/client.rs:110

• Invalid HTTPS proxy URLs are also silently ignored, which leaves HTTPS traffic without the requested custom proxy while the client still builds successfully. Propagate Proxy::https failures when proxy_url_for_https is provided so invalid per-client proxy settings are not accepted silently.

            if let Some(Ok(proxy_https)) = proxy_url_for_https.as_deref().map(Proxy::https) {
                builder = builder.proxy(proxy_https.no_proxy(no_proxy));
            }

backends/nsurlsession/src/client.rs:60

• A provided HTTPS proxy URL that fails parsing (including otherwise valid URLs without an explicit port) is silently dropped, so HTTPS requests will not use the caller's requested proxy. Treat an invalid proxy_url_for_https as a client build error or derive the default port from the scheme rather than ignoring it.

                        if let Some(https_proxy) =
                            proxy_url_for_https.and_then(|url| parse_proxy_host_port(&url))
                        {

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[bdbai]

@copilot apply changes based on the comments in this thread