docs: Add recent development summary to CONTEXT.md

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

CONTEXT.md

@@ -23,3 +23,18 @@ Development Summary:
     • Removed the initial colorful test cube from the main scene.
     • Fixed a build error caused by a typo (QMatrix4xá4 instead of QMatrix4x4) that was introduced during the cleanup.
     • Resolved a Qt6 compatibility issue by replacing a legacy Qt5 OpenGL header include with its modern equivalent.
+ 8 Sketch Creation Workflow:
+    • Implemented a sketch creation dialog that prompts the user to select a plane (XY, XZ, YZ).
+    • The viewport camera automatically orients itself to be normal to the chosen plane.
+    • Created a dedicated `SketchGrid` class to draw a 2D grid on the active sketch plane, complete with major/minor grid lines, labeled axes, and an origin point.
+    • Fixed a bug where the XY and XZ camera orientations were incorrect.
+ 9 Data Model and File Persistence:
+    • Designed and implemented a feature-based dependency graph model.
+    • Created a base `Feature` class and a concrete `SketchFeature` class.
+    • A `Document` class was created to manage the collection of features (the feature graph).
+    • Implemented JSON serialization for the document, allowing models to be saved to and loaded from disk.
+    • Added "New", "Open", "Save", and "Save As" functionality to the main file menu.
+10 Feature Browser UI:
+    • Added a dockable feature browser (tree view) to the left side of the main window.
+    • The browser displays the current document as the root node and lists all features (e.g., "Sketch") as children.
+    • The `Document` class now uses Qt signals and slots to notify the `MainWindow` of changes, ensuring the feature browser is always synchronized with the underlying data model.