feat: Phase 10.5 Python統合プラグインとAOTビルド対応

- Pythonプラグイン（PyRuntimeBox/PyObjectBox）を追加
  - eval, import, getattr, call, callKw, strメソッド実装
  - math.sqrtデモ等のサンプルコード追加
- AOTビルドサポート追加
  - libnyrtランタイムライブラリ
  - build_aot.shビルドスクリプト
- .gitignore改善
  - JSONLとDOTファイル除外
  - プラグインのビルド成果物除外
- 不要ファイル削除
  - nekocode-temp, zenn_articles
  - 一時的なログファイル類

Phase 10.1の新計画に基づいて、プラグインBox統一化を推進

examples/py_eval_demo.nyash

@@ -0,0 +1,16 @@
+// Python plugin demo (Phase 10.5 scaffold)
+// Requires: plugins/nyash-python-plugin built (release) and nyash.toml updated
+// Run:
+//   NYASH_CLI_VERBOSE=1 ./target/release/nyash --backend vm examples/py_eval_demo.nyash
+
+static box Main {
+  main() {
+    local py, obj
+    py = new PyRuntimeBox()
+    // Evaluate simple Python expression and print its string form
+    obj = py.eval("'hello' * 3")
+    me.console.log("py.eval.str=", obj.str())
+    return 0
+  }
+}
+

examples/py_kw_round_demo.nyash

@@ -0,0 +1,18 @@
+// Python plugin demo: kwargs call via callKw
+// Build plugin:
+//   (cd plugins/nyash-python-plugin && cargo build --release)
+// Run (with auto-decode optional):
+//   NYASH_PY_AUTODECODE=1 NYASH_CLI_VERBOSE=1 ./target/release/nyash --backend vm examples/py_kw_round_demo.nyash
+
+static box Main {
+  main() {
+    local py, bi, roundf, r
+    py = new PyRuntimeBox()
+    bi = py.import("builtins")
+    f = bi.getattr("int")
+    // int(x="FF", base=16) => 255
+    r = f.callKw("x", "FF", "base", 16)
+    me.console.log("int(x='FF', base=16)=", r.str())
+    return 0
+  }
+}

examples/py_math_sqrt_demo.nyash

@@ -0,0 +1,22 @@
+// Python plugin demo: import math, getattr sqrt, call(9), str()
+// Build plugin:
+//   (cd plugins/nyash-python-plugin && cargo build --release)
+// Run:
+//   NYASH_CLI_VERBOSE=1 ./target/release/nyash --backend vm examples/py_math_sqrt_demo.nyash
+
+static box Main {
+  init { console }
+  
+  main() {
+    me.console = new ConsoleBox()
+    
+    local py, m, f, r
+    py = new PyRuntimeBox()
+    m = py.import("math")
+    f = m.getattr("sqrt")
+    r = f.call(9)
+    print("sqrt(9) = " + r.str())
+    return 0
+  }
+}
+