NickServ: add SET AUTOOP per-account auto-op opt-out

A user with SET AUTOOP OFF is never auto-opped on join, even where they
hold channel access — they op themselves via ChanServ UP. Stored inverted
(no_autoop) so the default stays auto-op. Join gates on both the channel
setting and the account preference; either can opt out.

src/engine/db/account.rs

@@ -21,7 +21,7 @@ impl Db {
             ajoin: Vec::new(),
             suspension: None,
             memos: Vec::new(), memo_ignore: Vec::new(), memo_notify: true, memo_limit: None,
-            greet: String::new(),
+            greet: String::new(), no_autoop: false,
             vhost: None,
             vhost_request: None,
             last_seen: now(),
@@ -60,7 +60,7 @@ impl Db {
             ajoin: Vec::new(),
             suspension: None,
             memos: Vec::new(), memo_ignore: Vec::new(), memo_notify: true, memo_limit: None,
-            greet: String::new(),
+            greet: String::new(), no_autoop: false,
             vhost: None,
             vhost_request: None,
             last_seen: now(),
@@ -418,6 +418,22 @@ impl Db {
         Ok(())
     }
 
+    /// Set whether `account` wants to be auto-opped on join (NickServ SET AUTOOP).
+    pub fn set_account_autoop(&mut self, account: &str, on: bool) -> Result<(), RegError> {
+        let k = key(account);
+        if !self.accounts.contains_key(&k) {
+            return Err(RegError::Internal);
+        }
+        self.log.append(Event::AccountAutoOpSet { account: account.to_string(), on }).map_err(|_| RegError::Internal)?;
+        self.accounts.get_mut(&k).unwrap().no_autoop = !on;
+        Ok(())
+    }
+
+    /// Whether `account` wants auto-op on join (default true). Unknown = true.
+    pub fn account_wants_autoop(&self, account: &str) -> bool {
+        self.accounts.get(&key(account)).is_none_or(|a| !a.no_autoop)
+    }
+
     /// Replace `account`'s password with freshly derived credentials.
     pub fn set_credentials(&mut self, account: &str, creds: Credentials) -> Result<(), RegError> {
         let k = key(account);