feat(datums): initial commit — unified datum creator addon

Standalone addon that replaces three stock PartDesign datum commands
(Plane, Line, Point) with a single unified Create_DatumCreator command.

Features:
- 16 smart creation modes (7 plane, 4 axis, 5 point)
- Auto-detection engine: selects best mode from geometry selection
- Mode override combo for manual selection
- Dynamic parameter UI (offset, angle, position, XYZ)
- Edit panel with real-time parameter updates via AttachExtension
- Catppuccin Mocha themed plane styling via SDK theme tokens
- Injected into partdesign.body and partdesign.feature contexts

package.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<package format="1" xmlns="https://wiki.freecad.org/Package_Metadata">
+  <name>datums</name>
+  <description>Unified datum creator for Kindred Create</description>
+  <version>0.1.0</version>
+  <maintainer email="development@kindred-systems.com">Kindred Systems</maintainer>
+  <license file="LICENSE">LGPL-2.1-or-later</license>
+  <url type="repository">https://git.kindred-systems.com/kindred/datums</url>
+
+  <content>
+    <workbench>
+      <classname>DatumCommandProvider</classname>
+      <subdirectory>datums</subdirectory>
+    </workbench>
+  </content>
+
+  <kindred>
+    <min_create_version>0.1.0</min_create_version>
+    <load_priority>45</load_priority>
+    <dependencies>
+      <dependency>sdk</dependency>
+    </dependencies>
+  </kindred>
+</package>