fix(sub): quote Clash scalars a YAML parser would read as numbers (#6104)

A REALITY short-id like 2351e1 is valid hex, but as a bare YAML scalar the
resolution rules read it as the float 23510. mihomo hex-decodes the resulting
five-digit string, fails with "invalid REALITY short ID", and the whole
provider loads zero nodes — one proxy takes the entire subscription down.

The encoder quotes the forms it recognises (plain integers, hex, booleans)
but not the exponent-float form, and its own parser reads that token back as
a string, so nothing in a round-trip through it reveals the problem. Check
the values against the resolution rules instead, and force quotes on any
plain scalar that would resolve to a non-string.

Applied to every string in the document rather than to short-id alone: the
panel's own short-id generator emits random hex, and passwords, obfs-
passwords and pre-shared keys reach the output the same way. Unambiguous
values are untouched, so the document is otherwise byte-identical.

The existing Clash tests assert on the config map, never on the serialized
text, which is why this survived; the new tests assert on the output.

internal/sub/clash_service.go

@@ -103,7 +103,7 @@ func (s *SubClashService) GetClash(subId string, host string) (string, string, e
 		}
 	}
 
-	finalYAML, err := yaml.Marshal(config)
+	finalYAML, err := marshalClashYAML(config)
 	if err != nil {
 		return "", "", err
 	}