docs: add Japanese translate documents (#1812)

* docs: add Japanese documents (`ja/docs`)

* docs: add Japanese documents (`ja/codes`)

* docs: add Japanese documents

* Remove pythontutor blocks in ja/

* Add an empty at the end of each markdown file.

* Add the missing figures (use the English version temporarily).

* Add index.md for Japanese version.

* Add index.html for Japanese version.

* Add missing index.assets

* Fix backtracking_algorithm.md for Japanese version.

* Add avatar_eltociear.jpg. Fix image links on the Japanese landing page.

* Add the Japanese banner.

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Co-authored-by: krahets <krahets@163.com>

ja/codes/python/chapter_dynamic_programming/climbing_stairs_dfs.py

@@ -0,0 +1,28 @@
+"""
+File: climbing_stairs_dfs.py
+Created Time: 2023-06-30
+Author: krahets (krahets@163.com)
+"""
+
+
+def dfs(i: int) -> int:
+    """探索"""
+    # 既知の dp[1] と dp[2] は、それらを返す
+    if i == 1 or i == 2:
+        return i
+    # dp[i] = dp[i-1] + dp[i-2]
+    count = dfs(i - 1) + dfs(i - 2)
+    return count
+
+
+def climbing_stairs_dfs(n: int) -> int:
+    """階段登り：探索"""
+    return dfs(n)
+
+
+"""ドライバーコード"""
+if __name__ == "__main__":
+    n = 9
+
+    res = climbing_stairs_dfs(n)
+    print(f"{n} 段登り、合計 {res} 通りの解がある")