feat(plugins): add HTTP host service (#5095)

* feat(httpclient): implement HttpClient service for outbound HTTP requests in plugins

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(httpclient): enhance SSRF protection by validating host requests against private IPs

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(httpclient): support DELETE requests with body in HttpClient service

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(httpclient): refactor HTTP client initialization and enhance redirect handling

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor(http): standardize naming conventions for HTTP types and methods

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor example plugin to use host.HTTPSend for improved error management

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(plugins): fix IPv6 SSRF bypass and wildcard host matching

Fix two bugs in the plugin HTTP/WebSocket host validation:

1. extractHostname now strips IPv6 brackets when no port is present
(e.g. "[::1]" → "::1"). Previously, net.SplitHostPort failed for
bracketed IPv6 without a port, leaving brackets intact. This caused
net.ParseIP to return nil, bypassing the private/loopback SSRF guard.

2. matchHostPattern now treats "*" as an allow-all pattern. Previously,
a bare "*" only matched via exact equality, so plugins declaring
requiredHosts: ["*"] (like webhook-rs) had all requests rejected.

---------

Signed-off-by: Deluan <deluan@navidrome.org>

plugins/pdk/rust/nd-pdk-host/src/lib.rs

@@ -35,6 +35,7 @@
 //! - [`artwork`] - provides artwork public URL generation capabilities for plugins.
 //! - [`cache`] - provides in-memory TTL-based caching capabilities for plugins.
 //! - [`config`] - provides access to plugin configuration values.
+//! - [`http`] - provides outbound HTTP request capabilities for plugins.
 //! - [`kvstore`] - provides persistent key-value storage for plugins.
 //! - [`library`] - provides access to music library metadata for plugins.
 //! - [`scheduler`] - provides task scheduling capabilities for plugins.
@@ -63,6 +64,13 @@ pub mod config {
     pub use super::nd_host_config::*;
 }
 
+#[doc(hidden)]
+mod nd_host_http;
+/// provides outbound HTTP request capabilities for plugins.
+pub mod http {
+    pub use super::nd_host_http::*;
+}
+
 #[doc(hidden)]
 mod nd_host_kvstore;
 /// provides persistent key-value storage for plugins.