feat: Module 11 becomes 13; diff-tracks fuzzer; align the two reference tracks

- Rename course/11-break-your-engine to 13-break-your-engine and update every
  link and mention; start-module explains that Module 13 has no tests to start.
- tools/diff-tracks.mjs (npm run diff:tracks): stages both references of a
  module, generates a seeded random SpellGrid level and script per seed, pipes
  it to the Rust and TypeScript CLIs and diffs their output; crashes on one or
  both sides fail. stagePlay takes a module number.
- register_assembled: the TypeScript track compared only the text of an
  existing Assembled card, so a base re-registered with a new cost (or a
  different split) silently rewrote the earlier card. It now compares every
  field the engine reads, as Rust does (Modules 5-10).
  New test_05_assemble_never_rewrites_an_earlier_card.
- SpellGrid CLIs: coordinates and chooser numbers are 1-9 plain digits in both
  tracks (Rust accepted signs, TypeScript accepted "+2", "0x2", "1e0"); Rust
  quotes card names verbatim instead of with Debug escapes; Rust joins the
  minion list with "; " instead of rewriting ", ". Two new CLI tests per track.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

course/10-spellgrid/reference/rust/src/engine/spellgrid.rs

@@ -200,7 +200,7 @@ impl SpellGrid {
             )
         });
         match target {
-            None if chooses => Err(format!("{card:?} needs a target minion")),
+            None if chooses => Err(format!("\"{card}\" needs a target minion")),
             None => Ok(()),
             Some(id) => {
                 // Every id in `entities` was issued by the board, so `find` may ask about it.
@@ -218,7 +218,9 @@ impl SpellGrid {
     pub fn check_play(&self, card: &str, x: i32, y: i32) -> Result<(), String> {
         self.side.check_hand(card, CardType::Minion)?;
         if self.side.world.card(card).def.noun.is_none() {
-            return Err(format!("{card:?} has no noun: it can't stand on the grid"));
+            return Err(format!(
+                "\"{card}\" has no noun: it can't stand on the grid"
+            ));
         }
         if !self.level.board().in_bounds(x, y) {
             return Err(format!("({x}, {y}) is off the grid"));
@@ -303,14 +305,14 @@ impl CardSide {
 
     fn check_hand(&self, card: &str, card_type: CardType) -> Result<(), String> {
         if self.in_hand(card).is_none() {
-            return Err(format!("{card:?} is not in the hand"));
+            return Err(format!("\"{card}\" is not in the hand"));
         }
         if self.world.card(card).def.card_type != card_type {
             let kind = match card_type {
                 CardType::Minion => "minion",
                 CardType::Spell => "spell",
             };
-            return Err(format!("{card:?} is not a {kind}"));
+            return Err(format!("\"{card}\" is not a {kind}"));
         }
         Ok(())
     }