fix(clippy): allow derivable_impls lint (#558)

Many types in the codebase have manual Default implementations
for documentation purposes or code clarity.

Author: echobt

Cargo.toml

@@ -395,6 +395,8 @@ unnecessary_sort_by = "allow"
 iter_without_into_iter = "allow"
 # Allow modules with the same name as parent (test modules pattern)
 module_inception = "allow"
+# Allow manual Default impl instead of derive (sometimes needed for doc comments)
+derivable_impls = "allow"
 
 [profile.release]
 lto = "fat"