feat: Multi-format MeshIO, performance optimizations, bug fixes, and CI test suite

[Siddharth0089]

Summary of Changes

This PR introduces stability fixes, performance optimizations, native multi-format mesh I/O, and CI automation:

1. Native Multi-Format Mesh I/O (MeshIO)

• Adds lightweight, self-contained \MeshIO\ module supporting:
  • OBJ: Fast loading and export (using vendored tinyobjloader and native exporter).
  • STL: ASCII and binary reader/writer with automatic vertex welding via 3D spatial hashing (\PositionKey).
  • PLY: ASCII and binary (little-endian) reader and writer.
• Updated GUI Open/Save dialogs and headless CLI to accept .obj, .stl, and .ply.

2. Performance Optimizations

• Parallel Mesh Area: Parallelized \calculateMeshArea\ using \ bb::parallel_reduce\ for meshes with >= 1000 triangles, plus cached top-level mesh surface area.
• O(1) Stage Timing: Replaced linear string scanning under \m_stageTimingMutex\ with an \std::unordered_map\ index table.
• Adaptive Remesh Passes: Added configurable iterations (3 passes for >100k triangles, 4 for smaller meshes) in \IsotropicRemesher.
• Progress Tracking: Eliminated linear scanning over all island threads on every progress tick.
• Range Insert: Replaced manual element-by-element loops with range \insert\ during island vertex merging.

3. Correctness & Portability

• Silenced Release Logging: Wrapped heavy \std::cerr\ spam in \quadextractor.cpp\ inside #if AUTO_REMESHER_DEBUG\ blocks to eliminate I/O flushing overhead in release builds.
• Safe Island Connection Padding: Handled bounds padding cleanly during island connection merging in \�utoremesher.cpp\ to prevent truncation.
• Intel oneAPI Compatibility: Guarded TBB headers with __has_include(<oneapi/tbb/...>)\ in \parameterizer.cpp, \quadparameterizer.cpp, and \ramefield.cpp.
• Cross-Version Qt Compatibility: Modernized whitespace splitting in \MeshIO\ using \simplified().split(' ')\ for compatibility across Qt 5 and Qt 6.

4. Features & UX

• Hard Surface Mode: Implemented \ModelType::HardSurface\ logic (tightened 45 degree crease dihedral threshold, disabled normal smoothing), accessible in GUI sidebar and CLI (--model-type organic|hardsurface).
• Live Cancellation: Added \std::atomic m_cancelled\ in \AutoRemesher\ and \QuadMeshGenerator, wired up to the UI button.
• Undo / Redo Stack: 20-state history stack with standard \Ctrl+Z\ / \Ctrl+Y.
• Statistics Dialog: Phase execution timings accessible via \Help -> Statistics.
• Safe Widget Lifetimes: Replaced raw static widget pointers with safe \QPointer\ management in \mainwindow.cpp.

5. Tests & CI Automation

• Unit Test Runner (tests/): Full test suite covering vector math, format detection, OBJ/STL/PLY roundtrips, and pipeline cancellation.
• GitHub Actions (.github/workflows/development.yml): Automated Linux compilation, unit test execution, and smoke tests (both organic and hard surface modes).
• Grouped directory formatting in \ci/lint.sh.