feat(ast): add type system declaration nodes

Added AST structures for new type system:
- ConceptDecl: Base type definition
- SubConceptDecl: Enum or record subtype with SubConceptKind
- ConceptComparisonDecl: Compile-time enum mapping
- ConceptMapping: Individual mapping entry

Added Declaration enum variants and stubs throughout codebase
for LSP, resolve, and semantic analysis modules.

src/lsp/code_actions.rs

@@ -1704,6 +1704,9 @@ fn get_declaration_name(decl: &crate::syntax::ast::Declaration) -> String {
         | Declaration::Schedule(s) => s.name.clone(),
         | Declaration::Behavior(b) => b.name.clone(),
         | Declaration::Use(_) => "use".to_string(),
+        | Declaration::Concept(c) => c.name.clone(),
+        | Declaration::SubConcept(sc) => sc.name.clone(),
+        | Declaration::ConceptComparison(cc) => cc.name.clone(),
     }
 }
 
@@ -1722,6 +1725,9 @@ fn get_declaration_type_name(decl: &crate::syntax::ast::Declaration) -> &'static
         | Declaration::Schedule(_) => "Schedule",
         | Declaration::Behavior(_) => "Behavior",
         | Declaration::Use(_) => "Use",
+        | Declaration::Concept(_) => "Concept",
+        | Declaration::SubConcept(_) => "Sub Concept",
+        | Declaration::ConceptComparison(_) => "Concept Comparison",
     }
 }
 
@@ -1953,6 +1959,9 @@ fn get_declaration_span(decl: &crate::syntax::ast::Declaration) -> Span {
         | Declaration::Schedule(s) => s.span.clone(),
         | Declaration::Behavior(b) => b.span.clone(),
         | Declaration::Use(u) => u.span.clone(),
+        | Declaration::Concept(c) => c.span.clone(),
+        | Declaration::SubConcept(sc) => sc.span.clone(),
+        | Declaration::ConceptComparison(cc) => cc.span.clone(),
     }
 }
 

src/lsp/hover.rs

@@ -179,6 +179,9 @@ fn get_declaration_name(decl: &Declaration) -> Option<String> {
         | Declaration::Schedule(s) => Some(s.name.clone()),
         | Declaration::Behavior(b) => Some(b.name.clone()),
         | Declaration::Use(_) => None,
+        | Declaration::Concept(_) |
+        Declaration::SubConcept(_) |
+        Declaration::ConceptComparison(_) => None, // TODO: Implement hover for type system
     }
 }
 
@@ -196,6 +199,9 @@ fn format_declaration_hover(decl: &Declaration, _kind: &DeclKind) -> Hover {
         | Declaration::Schedule(s) => format_schedule_hover(s),
         | Declaration::Behavior(b) => format_behavior_hover(b),
         | Declaration::Use(_) => "**use** declaration".to_string(),
+        | Declaration::Concept(_) => "**concept** declaration".to_string(),
+        | Declaration::SubConcept(_) => "**sub_concept** declaration".to_string(),
+        | Declaration::ConceptComparison(_) => "**concept_comparison** declaration".to_string(),
     };
 
     Hover {

src/lsp/semantic_tokens.rs

@@ -407,6 +407,12 @@ pub fn get_semantic_tokens(doc: &Document) -> Option<SemanticTokensResult> {
                     }
                 }
             },
+            | Declaration::Concept(_) |
+            Declaration::SubConcept(_) |
+            Declaration::ConceptComparison(_) => {
+                // TODO: Implement semantic highlighting for type system
+                // declarations
+            },
         }
     }
 

src/lsp/symbols.rs

@@ -96,6 +96,9 @@ fn extract_declaration_symbol(
             extract_variant_symbols(&e.variants, positions),
         ),
         | Declaration::Use(_) => return None, // Use statements don't create symbols
+        | Declaration::Concept(_) |
+        Declaration::SubConcept(_) |
+        Declaration::ConceptComparison(_) => return None, // TODO: Implement symbols for type system
     };
 
     let (start_line, start_col) = positions.offset_to_position(span.start);