feat(highlight): add Java highlighting support

Cargo.toml

@@ -42,6 +42,7 @@ tree-sitter-md = "0.3"
 tree-sitter-c-sharp = "0.23"
 tree-sitter-ruby = "0.23"
 tree-sitter-elixir = "0.3"
+tree-sitter-java = "0.23"
 tree-sitter-zig = "1.1.2"
 once_cell = "1.20"
 arboard = "3.4"

src/command/diff/highlight/config.rs

@@ -6,6 +6,9 @@ use super::queries::*;
 // Elixir uses the bundled highlight queries from tree-sitter-elixir
 const ELIXIR_HIGHLIGHTS: &str = tree_sitter_elixir::HIGHLIGHTS_QUERY;
 
+// Java uses the bundled highlight queries from tree-sitter-java
+const JAVA_HIGHLIGHTS: &str = tree_sitter_java::HIGHLIGHTS_QUERY;
+
 pub const HIGHLIGHT_NAMES: &[&str] = &[
     "attribute",
     "comment",
@@ -214,6 +217,14 @@ pub static CONFIGS: Lazy<Vec<(&'static str, LanguageConfig)>> = Lazy::new(|| {
         &mut configs,
     );
 
+    load_config(
+        tree_sitter_java::LANGUAGE.into(),
+        "java",
+        JAVA_HIGHLIGHTS,
+        "java",
+        &mut configs,
+    );
+
     load_config(
         tree_sitter_zig::LANGUAGE.into(),
         "zig",

src/command/diff/highlight/mod.rs

@@ -238,6 +238,7 @@ mod tests {
         assert!(extensions.contains(&"json"), "JSON config should be loaded");
         assert!(extensions.contains(&"ex"), "Elixir config should be loaded");
         assert!(extensions.contains(&"exs"), "Elixir script config should be loaded");
+        assert!(extensions.contains(&"java"), "Java config should be loaded");
         assert!(extensions.contains(&"zig"), "Zig config should be loaded");
     }
 
@@ -303,6 +304,22 @@ end
         assert!(has_highlights, "Elixir code should have syntax highlights");
     }
 
+    #[test]
+    fn test_java_highlighting() {
+        let code = r#"package com.example;
+
+public class Hello {
+    public static void main(String[] args) {
+        System.out.println("Hello, Java!");
+    }
+}
+"#;
+        let result = highlight_code(code, "test.java");
+        assert!(!result.is_empty(), "Java highlighting should produce output");
+        let has_highlights = result.iter().any(|(_, h)| h.is_some());
+        assert!(has_highlights, "Java code should have syntax highlights");
+    }
+
     #[test]
     fn test_zig_highlighting() {
         let code = r#"const std = @import("std");