feat(plugins): add similar songs retrieval functions and improve duration consistency (#4933)

* feat: add duration filtering for similar songs matching

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

* test: refactor expectations for similar songs in provider matching tests

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

* feat(plugins): add functions to retrieve similar songs by track, album, and artist

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

* fix(plugins): support uint32 in ndpgen

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

* fix(plugins): update duration field to use seconds as float instead of milliseconds as uint32

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

* fix: add helper functions for Rust's skip_serializing_if with numeric types

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

* feat(provider): enhance track matching logic to fallback to title match when duration-filtered tracks fail

---------

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

plugins/pdk/rust/nd-pdk-capabilities/src/scheduler.rs

@@ -4,6 +4,20 @@
 // It is intended for use in Navidrome plugins built with extism-pdk.
 
 use serde::{Deserialize, Serialize};
+
+// Helper functions for skip_serializing_if with numeric types
+#[allow(dead_code)]
+fn is_zero_i32(value: &i32) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_u32(value: &u32) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_i64(value: &i64) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_u64(value: &u64) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_f32(value: &f32) -> bool { *value == 0.0 }
+#[allow(dead_code)]
+fn is_zero_f64(value: &f64) -> bool { *value == 0.0 }
 /// SchedulerCallbackRequest is the request provided when a scheduled task fires.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]