lexicon: Initialize project

Cargo.toml

···
 edition = "2024"
 
 [workspace]
-members = ["footnotes_appview", "footnotes_core"]
+members = ["footnotes_appview", "footnotes_core", "footnotes_lexicon"]
 resolver = "2"

footnotes_lexicon/Cargo.toml

···
+[package]
+name = "footnotes_lexicon"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

footnotes_lexicon/src/lib.rs

···
+pub fn add(left: u64, right: u64) -> u64 {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}