feat: add PPTX editing and creation skills with comprehensive documentation

- Introduced new skills for editing and creating PPTX presentations, including a detailed guide on template-based workflows and script usage.
- Added scripts for slide management, cleaning, and packing PPTX files, enhancing the overall functionality for users.
- Included a LICENSE file to clarify usage rights and restrictions.
- Created a SKILL.md file to provide an overview and quick reference for PPTX-related tasks.
- Documented various formatting rules, common pitfalls, and design ideas to improve presentation quality.

skills/pptx/scripts/office/schemas/ISO-IEC29500-4_2016/shared-customXmlDataProperties.xsd

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+  xmlns="http://schemas.openxmlformats.org/officeDocument/2006/customXml"
+  xmlns:s="http://schemas.openxmlformats.org/officeDocument/2006/sharedTypes"
+  targetNamespace="http://schemas.openxmlformats.org/officeDocument/2006/customXml"
+  elementFormDefault="qualified" attributeFormDefault="qualified" blockDefault="#all">
+  <xsd:import namespace="http://schemas.openxmlformats.org/officeDocument/2006/sharedTypes"
+    schemaLocation="shared-commonSimpleTypes.xsd"/>
+  <xsd:complexType name="CT_DatastoreSchemaRef">
+    <xsd:attribute name="uri" type="xsd:string" use="required"/>
+  </xsd:complexType>
+  <xsd:complexType name="CT_DatastoreSchemaRefs">
+    <xsd:sequence>
+      <xsd:element name="schemaRef" type="CT_DatastoreSchemaRef" minOccurs="0" maxOccurs="unbounded"
+      />
+    </xsd:sequence>
+  </xsd:complexType>
+  <xsd:complexType name="CT_DatastoreItem">
+    <xsd:sequence>
+      <xsd:element name="schemaRefs" type="CT_DatastoreSchemaRefs" minOccurs="0"/>
+    </xsd:sequence>
+    <xsd:attribute name="itemID" type="s:ST_Guid" use="required"/>
+  </xsd:complexType>
+  <xsd:element name="datastoreItem" type="CT_DatastoreItem"/>
+</xsd:schema>