Clean up relay validation

backend/Cargo.lock

@@ -210,6 +210,7 @@ dependencies = [
  "nostr-sdk",
  "nwc",
  "rand 0.8.5",
+ "regex",
  "reqwest",
  "serde",
  "serde_json",
@@ -1894,6 +1895,18 @@ dependencies = [
  "bitflags",
 ]
 
+[[package]]
+name = "regex"
+version = "1.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e10754a14b9137dd7b1e3e5b0493cc9171fdd105e0ab477f51b72e7f3ac0e276"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "regex-automata"
 version = "0.4.14"