Feat: more predictable projet load behavior

crates/project/src/project.rs

@@ -450,6 +450,8 @@ pub struct Project {
     pub sample_paths: Vec<PathBuf>,
     #[serde(default = "default_tempo")]
     pub tempo: f64,
+    #[serde(default)]
+    pub playing_patterns: Vec<(usize, usize)>,
 }
 
 fn default_tempo() -> f64 {
@@ -462,6 +464,7 @@ impl Default for Project {
             banks: (0..MAX_BANKS).map(|_| Bank::default()).collect(),
             sample_paths: Vec::new(),
             tempo: default_tempo(),
+            playing_patterns: Vec::new(),
         }
     }
 }