Docs rewrite

content/docs/guide/variables.mdx

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+---
+title: Variables
+description: Variable declarations, mutability, type annotations, and destructuring.
+icon: Variable
+---
+
+```mist
+let x = 42;                    // Type-inferred immutable
+let mut y = 10;                // Mutable variable
+i32 z = 100;                   // Explicit type annotation
+str& s = "hello";              // Typed string reference
+bool b = true;                 // Typed boolean
+f64 f = 3.14;                  // Typed float
+let (a, b) = (1, "two");      // Destructuring
+let (x, (y, z)) = (1, (2, 3)); // Nested destructuring
+```
+
+Variable declarations follow either of two forms:
+
+```mist
+let <pattern> [= <expr>];
+<type> <pattern> [= <expr>];
+```
+
+### Const and Static
+
+```mist
+const MAX: i32 = 100;
+static NAME: str& = "hello";
+```