fix(upgrade): errors from Rust 2024 edition

- gen is a reserved keyword (→ renamed module to generator)
- ref in patterns with implicit borrowing (→ removed ref)
- & pattern with implicit borrowing (→ added & to outer pattern)

src/import/wizard.rs

@@ -140,7 +140,7 @@ impl ImportPipeline {
         }
 
         // Create derived date-component categories
-        for (_, _, _, ref derived_name) in &date_extractions {
+        for (_, _, _, derived_name) in &date_extractions {
             model.add_category(derived_name)?;
         }
 
@@ -176,7 +176,7 @@ impl ImportPipeline {
                         coords.push((cat_proposal.field.clone(), v.clone()));
 
                         // Extract date components from this field's value
-                        for (field, fmt, comp, ref derived_name) in &date_extractions {
+                        for (field, fmt, comp, derived_name) in &date_extractions {
                             if *field == cat_proposal.field {
                                 if let Some(derived_val) = extract_date_component(&v, fmt, *comp) {
                                     if let Some(cat) = model.category_mut(derived_name) {

src/main.rs

@@ -371,7 +371,7 @@ fn run_headless_script(script_path: &PathBuf, file: &Option<PathBuf>) -> Result<
 // ── Helpers ──────────────────────────────────────────────────────────────────
 
 fn get_initial_model(file_path: &Option<PathBuf>) -> Result<Model> {
-    if let Some(ref path) = file_path {
+    if let Some(path) = file_path {
         if path.exists() {
             let mut m = persistence::load(path)
                 .with_context(|| format!("Failed to load {}", path.display()))?;

src/persistence/mod.rs

@@ -2118,7 +2118,7 @@ mod parser_edge_cases {
 // files.  The generator and parser share a single source of truth: the grammar.
 
 #[cfg(test)]
-mod gen {
+mod generator {
     use pest_meta::ast::{Expr, RuleType};
     use pest_meta::parser;
     use proptest::prelude::*;
@@ -2253,15 +2253,15 @@ mod gen {
         // Use random bytes as entropy for choices in the grammar walk
         prop::collection::vec(any::<u8>(), 64..=256).prop_map(|choices| {
             let rules = load_grammar();
-            let mut gen = Gen::new(&rules, choices);
-            gen.generate("file")
+            let mut g = Gen::new(&rules, choices);
+            g.generate("file")
         })
     }
 }
 
 #[cfg(test)]
 mod grammar_prop_tests {
-    use super::{format_md, gen, parse_md};
+    use super::{format_md, generator, parse_md};
     use proptest::prelude::*;
 
     proptest! {
@@ -2269,7 +2269,7 @@ mod grammar_prop_tests {
 
         /// parse(generate()) — every generated file parses without error.
         #[test]
-        fn generated_file_parses(file in gen::improv_file()) {
+        fn generated_file_parses(file in generator::improv_file()) {
             let result = parse_md(&file);
             prop_assert!(result.is_ok(),
                 "Generated file failed to parse:\n{}\nError: {}",
@@ -2278,7 +2278,7 @@ mod grammar_prop_tests {
 
         /// parse(print(parse(generate()))) — round-trip through format is stable.
         #[test]
-        fn generated_file_roundtrips(file in gen::improv_file()) {
+        fn generated_file_roundtrips(file in generator::improv_file()) {
             let result1 = parse_md(&file);
             // Skip inputs that don't parse (the grammar walk may produce
             // degenerate inputs like empty model names)

src/view/types.rs

@@ -121,7 +121,7 @@ impl View {
     pub fn categories_on(&self, axis: Axis) -> Vec<&str> {
         self.category_axes
             .iter()
-            .filter(|(_, &a)| a == axis)
+            .filter(|&(_, &a)| a == axis)
             .map(|(n, _)| n.as_str())
             .collect()
     }