Add say story

exercises/say/instructions.md

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+# Instructions
+
+Given a number, your task is to express it in English words exactly as your friend should say it out loud.
+Yaʻqūb expects to use numbers from 0 up to 999,999,999,999.
+
+Examples:
+
+- 0 → zero
+- 1 → one
+- 12 → twelve
+- 123 → one hundred twenty-three
+- 1,234 → one thousand two hundred thirty-four

exercises/say/introduction.md

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+# Introduction
+
+Your friend Yaʻqūb works the counter at the busiest deli in town, slicing, weighing, and wrapping orders for a never-ending line of hungry customers.
+To keep things moving, each customer takes a numbered ticket when they arrive.
+
+When it’s time to call the next person, Yaʻqūb reads their number out loud, always in full English words to make sure everyone hears it clearly.