drop the operator pronoun sentence from the agent system prompt

Not every swarm's operator is she/her. The prompt now names no pronouns
and tells agents to say "the operator"; pronouns will come from a
per-operator profile setting. The operatorPronouns removal warning and
claude-invocation.md say the same.

hive-agent/src/prompt.rs

@@ -232,11 +232,12 @@ shared closer
     }
 
     #[test]
-    fn render_substitutes_label_and_keeps_the_pronoun_line() {
+    fn render_substitutes_label_and_names_no_operator_pronouns() {
         // Real template's first agent line.
         let rendered = render(&PRODUCTION_TEMPLATE, "alice", None, None, None);
         assert!(rendered.contains("hyperhive agent `alice`"));
-        assert!(rendered.contains("uses **she/her** pronouns"));
+        assert!(rendered.contains("say \"the operator\""));
+        assert!(!rendered.contains("pronoun"));
         assert!(!rendered.contains("{label}"));
         assert!(!rendered.contains("{operator_pronouns}"));
     }