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

src/parser.rs

@@ -21,6 +21,7 @@ use crate::value::*;
 use crate::*;
 
 use alloc::collections::BTreeMap;
+use core::num::NonZeroU32;
 use core::str::FromStr;
 
 use anyhow::{anyhow, bail, Result};
@@ -198,6 +199,10 @@ impl<'source> Parser<'source> {
         }
     }
 
+    pub fn set_max_col(&mut self, max_col: NonZeroU32) {
+        self.lexer.set_max_col(max_col);
+    }
+
     pub fn get_path_ref_components_into(refr: &Ref<Expr>, comps: &mut Vec<Span>) -> Result<()> {
         match refr.as_ref() {
             Expr::RefDot { refr, field, .. } => {