Add Ruby AST support using tree-sitter-ruby

- Added `tree-sitter-ruby` dependency to `Cargo.toml` and `Cargo.lock`.
- Introduced `patterns/ruby.rs` with Ruby-specific AST patterns for vulnerability detection.
- Updated `patterns/mod.rs` and `ast.rs` to support Ruby AST parsing and pattern registry initialization.

Cargo.lock

@@ -615,6 +615,7 @@ dependencies = [
  "tree-sitter-javascript",
  "tree-sitter-php",
  "tree-sitter-python",
+ "tree-sitter-ruby",
  "tree-sitter-rust",
  "tree-sitter-typescript",
 ]
@@ -1254,6 +1255,16 @@ dependencies = [
  "tree-sitter-language",
 ]
 
+[[package]]
+name = "tree-sitter-ruby"
+version = "0.23.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be0484ea4ef6bb9c575b4fdabde7e31340a8d2dbc7d52b321ac83da703249f95"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
 [[package]]
 name = "tree-sitter-rust"
 version = "0.24.0"