Add multilingual exercise code (#1959)

Replace the exercise pages' Python-only snippets with source-backed implementations for the 13 visible programming languages, and localize reader-facing comments by site language. Zig remains out of scope.

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codes/rust/chapter_divide_and_conquer/fast_power.rs

@@ -0,0 +1,23 @@
+/*
+ * File: fast_power.rs
+ * Created Time: 2026-08-18
+ * Author: Hello Algo Team
+ */
+
+/* 快速幂 */
+fn fast_pow(x: i32, n: i32) -> i32 {
+    if n == 0 {
+        return 1;
+    }
+    let half = fast_pow(x, n / 2);
+    if n % 2 == 0 {
+        return half * half;
+    }
+    half * half * x
+}
+
+fn main() {
+    assert_eq!(fast_pow(7, 0), 1);
+    assert_eq!(fast_pow(3, 5), 243);
+    assert_eq!(fast_pow(2, 6), 64);
+}