feat(parser): add action parameters, repeater decorator, and named participants

Add syntax enhancements for more expressive behavior trees and relationships.

Action parameters:
- Support typed/positional parameters: WaitDuration(2.0)
- Support named parameters: SetValue(field: value)
- Enable inline values without field names

Repeater decorator:
- Add * { node } syntax for repeating behavior nodes
- Maps to Decorator("repeat", node)

Named participant blocks:
- Replace self/other blocks with named participant syntax
- Support multi-party relationships
- Example: Alice { role: seeker } instead of self { role: seeker }

Schedule block syntax:
- Require braces for schedule blocks to support narrative fields
- Update tests to use new syntax: 04:00 -> 06:00: Activity { }

src/error_showcase_tests.rs

@@ -134,12 +134,14 @@ fn test_duplicate_definition_error() {
         declarations: vec![
             Declaration::Character(Character {
                 name: "Martha".to_string(),
+                species: None,
                 fields: vec![],
                 template: None,
                 span: Span::new(0, 10),
             }),
             Declaration::Character(Character {
                 name: "Martha".to_string(),
+                species: None,
                 fields: vec![],
                 template: None,
                 span: Span::new(20, 30),
@@ -207,6 +209,7 @@ fn test_unknown_life_arc_state_error() {
         states: vec![
             ArcState {
                 name: "child".to_string(),
+                on_enter: None,
                 transitions: vec![Transition {
                     to: "adult".to_string(), // 'adult' exists
                     condition: Expr::BoolLit(true),
@@ -216,6 +219,7 @@ fn test_unknown_life_arc_state_error() {
             },
             ArcState {
                 name: "adult".to_string(),
+                on_enter: None,
                 transitions: vec![Transition {
                     to: "senior".to_string(), // 'senior' doesn't exist!
                     condition: Expr::BoolLit(true),
@@ -323,6 +327,7 @@ fn test_schedule_overlap_error() {
                     minute: 30,
                     second: 0,
                 },
+                fields: vec![],
                 span: Span::new(0, 50),
             },
             ScheduleBlock {
@@ -337,6 +342,7 @@ fn test_schedule_overlap_error() {
                     minute: 0,
                     second: 0,
                 },
+                fields: vec![],
                 span: Span::new(50, 100),
             },
         ],
@@ -413,6 +419,7 @@ fn test_relationship_bond_out_of_range() {
 fn test_duplicate_field_in_convert() {
     let character = Character {
         name: "Martha".to_string(),
+        species: None,
         fields: vec![
             Field {
                 name: "age".to_string(),