use a neutral forge name in link-form placeholders, schema examples and tests

Codeberg does not accept AI-assisted contributions, so it should not be
the example we put in front of operators. The placeholders now read
myforge / forge.example.org; the tests use the same neutral names.

hive-types/src/lib.rs

@@ -196,7 +196,7 @@ mod ident_tests {
             "damocles",
             "hm1nd",
             "agent-with-dashes",
-            "codeberg",
+            "myforge",
             "acct-1",
         ] {
             assert!(Ident::parse(ok).is_ok(), "should accept {ok:?}");