Merge upstream changes with comprehensive conflict resolution

[DzmingLi]

This pull request merges the latest features, performance optimizations, and architectural improvements from the upstream branch while carefully preserving and integrating PLCTLab's unique enhancements, such as RISC-V backend support, robust error handling, and advanced trait analysis.

Major Architectural Upgrades & Feature Enhancements

1. Pattern Matching Engine Overhaul (check_match.ml)

• Adopted Upstream Architecture: The upstream version provides a complete architectural rewrite of the pattern matching engine, offering a cleaner structure and more powerful features.
• New Features:
  • Optimization for string array patterns (try_combine_array_pat_to_string).
  • Support for Texpr_guard_let and Texpr_is expressions.
  • Better separation of concerns: analyze_cases for analysis and check_match for reporting.
• Benefit: This provides a functional superset, enhancing all of PLCTLab's original functionality while adding support for new language constructs.

2. Hybrid Compilation Architecture (driver_util.ml, moon0_main.ml)

• Dual-Target Support Preserved: A hybrid compilation pipeline was created to preserve both PLCTLab's RISC-V backend (riscv_gen) and upstream's unified WASM backend (wasm_gen with dwarfsm_callback).
• Modernized Package Management: Adopted upstream's package table system for better package isolation and management.
• Backward-Compatible CLI: Retained the wat_gen function for text format (.wat) output while integrating dwarfsm_callback for modern binary (.wasm) output.
• Benefit: This approach adopts the modern upstream WASM pipeline and Shrink_wasmir optimizer without losing critical RISC-V target support.

3. Trait Analysis System Integration (placeholder_env.ml, toplevel_typer.ml)

• Hybrid Trait Analysis: Fully preserved PLCTLab's powerful trait object safety analysis and compile-time processing for foreign traits.
• Integrated Upstream Enhancements: Seamlessly integrated upstream's trait alias support and handling for new types like Ptd_extern and Ptype_object.
• Benefit: Achieved zero functionality loss while gaining all trait-related features from both branches, maximizing functionality.

4. Dependency Analysis Algorithm Upgrade (topo_sort.ml)

• Adopted Superior Upstream Implementation: The upstream version uses an efficient set-based algorithm and performs a comprehensive dependency analysis on entire implementations, not just expressions.
• Functional Enhancements:
  • More efficient variable tracking.
  • More robust self-reference and dependency cycle detection.
  • Compatibility with the modern type system, including trait_alias.
• Benefit: Gained a more accurate and efficient topological sorting algorithm capable of handling more complex code structures.

5. Async Function Support (parsing_ast_lint.ml)

• Adopted Upstream Implementation: Added full async support to the function desugaring process.
• Guard Expression Support: Pattern matching now supports guard conditions, enhancing the language's expressive power.
• Benefit: Aligns the compiler with the latest MoonBit language features, especially the asynchronous programming model.

Performance Optimizations

• List Operations (basic_lst.ml): Adopted upstream's highly optimized implementations for core list functions (e.g., map, fold_right, map2, iteri). These implementations leverage techniques like special casing for small lists (1-10 elements), tail-recursion optimization, and chunked processing to significantly improve performance while maintaining API compatibility. PLCTLab's unique functions like group and stable_group were preserved.

Robustness, Correctness & Error Handling

• File I/O Error Handling (core_format.ml, parsing_parse.ml): Kept PLCTLab's comprehensive try...with Sys_error pattern, which is more robust than upstream's file existence checks as it handles permissions, disk errors, and other scenarios while providing more detailed error messages.
• DWARF Debug Information (dwarfsm_encode_wasm.ml): Preserved PLCTLab's tracking of low_pc and high_pc, ensuring the integrity of DWARF debugging information, which is essential for debugging.
• Package Import System (pkg.ml): Adopted upstream's safer import mechanism, which detects and prevents name collisions between imported and local definitions, improving code reliability.
• Label Semantics (label.ml): Maintained PLCTLab's safer approach to label comparison/hashing, which considers both name and stamp fields, making it more robust than upstream's stamp-only method.
• Type System Completeness (mtype.ml, name_mangle.ml): Ensured that all types (including new additions like T_int16, T_uint16, T_raw_func) are handled correctly during serialization and name mangling, preventing potential runtime errors from incomplete pattern matches.

Code Quality & Consistency

• Code Style Unification: In multiple modules (e.g., basic_core_ident.ml, object_util.ml, trait_impl.ml), preferred PLCTLab's clean, manually written implementations over verbose, auto-generated code from upstream for better readability.
• Code Deduplication (typer.ml): Eliminated over 270 lines of duplicated code (for record updates, field access, etc.) in PLCTLab's assignment operator logic, as the functionality already existed elsewhere in the file.
• Parameter Order Correction (basic_lst.ml): Corrected the parameter order of the take function from take n xs to take xs n to align with all other call sites in the project and OCaml community conventions. All relevant call sites were updated.
• API Modernization (mcore_util.ml, monofy_worklist.ml): Standardized the use of the internal Lst module and adopted modern function signature styles (e.g., labeled arguments ~f:), improving code consistency and readability across the project.