made book mark for infinite canvas with position zoom and page

[h-990]

Feature Proposal: Native Document Bookmarking System & Apple Silicon Optimization 🚀

Hi everyone! I've been working on a massive quality-of-life improvement for navigating large and complex files in OpenBoard. I've successfully implemented a Native C++ Bookmarking System, allowing users to save, rename, and instantly teleport to specific spatial coordinates and pages across infinite whiteboards.

Simultaneously, I resolved some lingering legacy build constraints and upgraded the compilation pipeline to natively support Apple Silicon (M-Series) via C++20.

Here is a breakdown of the architectural additions and features implemented in this branch:

🌟 Key UI/UX Features

• New Bookmarks Panel (UBBookmarksWidget): Integrated a new interactive widget into the left-side Dock Palette.
  • Easily toggleable via the Ctrl+B shortcut.
  • Users can Add a bookmark to capture the immediate viewport location.
  • Includes a UI to Rename bookmarks via a native QInputDialog for personalized organization (e.g., "Math Graph" or "Lecture End").
  • Users can safely Remove bookmarks natively.
• Smart Teleportation: Selecting a saved Bookmark dynamically tracks the document state. If a user is on Page 5 but clicks a bookmark taken on Page 1, the controller will autonomously execute setActiveDocumentScene(targetPage) before navigating, teleporting the user perfectly over to the correct whiteboard layout.

🛠️ Core Architecture Integration

• Sub-Pixel Coordinate Rendering: Bypassed the standard visual canvas boundaries (mapToScene()) which tend to drift due to scrollbars. Instead, the logic calculates symmetric sub-pixel bounds heavily relying on the raw QTransform graphic matrix inversion (x = -transform.m31() / m11()) ensuring pixel-perfect centerOn() restorations.
• metadata.rdf Persistence: Tightly wove the bookmark state into UBMetadataDcSubsetAdaptor. Bookmarks are serialized via QJsonDocument into the standard .ubz / .rdf architecture so endpoints persist permanently across computing sessions and file transfers without creating isolated local databases.
• Robust 64-Bit Data Safety: Implemented rigorous QString parsing over standard toInt() bounds for Bookmark IDs (which rely on millisecond Epoch time generation) resolving edge-case integer overflows during deletion cycles.

🍏 Compilation & Apple Silicon (M4) Portability

• Modernized Standard to C++20: Forced CONFIG += c++20 within OpenBoard.pro to finally stabilize compilation warnings and natively support Apple Silicon Poppler APIs (which recently removed raw pointer bridging in favor of legacy-dropping reference tracking like std::span).
• Architectural Cleanup: Skipped Rosetta translation requirements and avoided framework duplication bugs by isolating the macdeployqt packaging parameters securely to QMAKE_APPLE_DEVICE_ARCHS = arm64.

📂 Modified Core Files

• src/board/UBBoardController.cpp & .h (Coordinate Mapping & Scene Flips)
• src/gui/UBBookmarksWidget.cpp & .h (GUI Components & QListWidget Setup)
• src/board/UBBoardPaletteManager.cpp (Left Dock Registration)
• src/adaptors/UBMetadataDcSubsetAdaptor.cpp (RDF Serialization)
• src/core/UBSettings.cpp (Metadata Key Registration)
• OpenBoard.pro (C++20 Flag & ABI Locks)

I have heavily tested the build bounds locally on an M4 Mac environments, and it natively supports all Homebrew architectures securely. I'd love to hear the team's thoughts on this addition or answer any structural questions regarding the implementation approach before submitting the PR diffs!

Thanks!