feat: add unified cleanup infrastructure and Grammar2 support

Memory Management:
- Add UnifiedCleanupManager bridging LinearTypeChecker with DropManager
- Implement HirLinearityKind enum mirroring TypedAST linearity kinds
- Add CleanupInfo for type cleanup requirements
- Create CleanupAction enum for destructor/intrinsic/drop operations
- Implement scope-based cleanup with strategy-aware action generation
- Integrate StackPromotionPass into MemoryManagementPass pipeline

ZynML:
- Add Grammar2 support for direct TypedAST parsing
- Export Grammar2, Grammar2Error, Grammar2Result types
- Add parse_to_typed_ast() and parse_to_typed_ast_with_filename() methods
- Add has_grammar2() and grammar2() accessor methods
- Add Grammar2 compilation and metadata tests

Author: darmie

crates/compiler/src/lib.rs

@@ -72,7 +72,10 @@ pub use monomorphize::{MonomorphizationContext, monomorphize_module};
 pub use pattern_matching::{PatternMatchCompiler, DecisionNode, check_exhaustiveness};
 pub use memory_management::{
     MemoryStrategy, MemoryContext, ARCManager, DropManager, EscapeAnalysis,
-    RefCountInfo, EscapeInfo, AllocationInfo
+    RefCountInfo, EscapeInfo, AllocationInfo, StackPromotionPass,
+    // Unified cleanup types
+    UnifiedCleanupBehavior, HirLinearityKind, CleanupInfo, UnifiedCleanupManager,
+    ScopeCleanupInfo, CleanupAction, convert_linearity_kind,
 };
 pub use memory_pass::MemoryManagementPass;
 pub use memory_optimization::MemoryOptimizationPass;