feat: make policy length limits configurable per engine (#624)

- Add PolicyLengthConfig struct with max_col, max_file_bytes, and
  max_lines fields, replacing hardcoded constants in the lexer.
- Add Engine::set_policy_length_config and clear_policy_length_config
  to allow callers to override the default limits.
- Add Source::from_contents_with_limits and from_file_with_limits for
  direct Source construction with custom limits; existing from_contents
  and from_file signatures are preserved using defaults.
- Add tests for default rejection, custom limits, and engine plumbing.
- Add bindings for C, C++, Python, WASM/JS, Java, Ruby, C#, Go

bindings/ruby/test/test_regorus.rb

@@ -183,6 +183,11 @@ class TestRegorus < Minitest::Test
     assert_equal ["<query.rego>:1: Hello"], @engine.take_prints
   end
 
+  def test_set_policy_length_config
+    @engine.set_policy_length_config({ max_col: 2000, max_file_bytes: 1048576, max_lines: 20000 })
+    @engine.clear_policy_length_config
+  end
+
   def alice_results
     {
       result: [