A group may hold a page's responsibility

responsible: { name, contact, group } says the address is a group's
inbox, not a person: no account or mail is made for it, and any
signed-in member of the group gets the suggest-a-change card. A
board's shared address was onboarded as a person before this.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

src/content/mod.rs

@@ -296,6 +296,13 @@ pub struct Responsible {
     /// A mailto address or plain email - deliberately just a string,
     /// same as everywhere else content keeps contact info simple.
     pub contact: String,
+    /// The group that holds the responsibility, when it is a group's
+    /// and not one person's: the board's inbox, not the board's
+    /// secretary. Then the address gets no account of its own (see
+    /// `seed.rs`), and any signed-in member of the group may suggest a
+    /// change to the page.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub group: Option<String>,
 }
 
 /// Whether to render `question`'s alternatives or its sign-in gate for