custom ecb is dynamic table and not system table from now on2

web/src/schema/mod.rs

@@ -1235,11 +1235,12 @@ pub(crate) const MAX_TABLE_NAME_LENGTH: usize = MAX_IDENTIFIER_LENGTH
 /// constants of three server modules rather than anything the catalog carries.
 /// A name the server adds to that set is a name this list will not know about
 /// until it is added here as well.
-pub(crate) const RESERVED_TABLE_NAMES: [&str; 4] = [
+pub(crate) const RESERVED_TABLE_NAMES: [&str; 5] = [
     "general_ledger",
     "journal_lines",
     "quantity_ledger",
     LEDGER_ACCOUNTS_TABLE,
+    "custom_exchange_rates",
 ];
 
 /// The identifier rules, plus the two a table name alone is held to.