feat: Prepare for code modularization and cleanup

- Archive old documentation and test files to `docs/archive/` and `local_tests/`.
- Remove various temporary and old files from the project root.
- Add `nekocode-rust` analysis tool and its output files (`nekocode/`, `.nekocode_sessions/`, `analysis.json`).
- Minor updates to `apps/chip8_nyash/chip8_emulator.nyash` and `local_tests` files.

This commit cleans up the repository and sets the stage for further code modularization efforts, particularly in the `src/interpreter` and `src/parser` modules, based on recent analysis.

local_tests/test_buffer_simple.nyash

@@ -0,0 +1,15 @@
+// シンプルなBufferBoxテスト
+static box Main {
+    main() {
+        print("BufferBox基本テスト開始")
+        
+        local buffer = new BufferBox()
+        print("BufferBox作成完了")
+        
+        // 基本メソッドテスト
+        local len = buffer.length()
+        print("length: " + len)
+        
+        return "complete"
+    }
+}