Refactor anti-injection system into modular subpackages

Split the anti-prompt-injector module into core, processors, management, and decision submodules for better maintainability and separation of concerns. Moved and refactored detection, shielding, statistics, user ban, message processing, and counter-attack logic into dedicated files. Updated imports and initialization in __init__.py and anti_injector.py to use the new structure. No functional changes to detection logic, but code organization is significantly improved.

src/__init__.py

@@ -0,0 +1,62 @@
+import random
+from typing import List, Optional, Sequence
+from colorama import init, Fore
+
+from src.common.logger import get_logger
+
+egg = get_logger("小彩蛋")
+
+def weighted_choice(data: Sequence[str],
+                    weights: Optional[List[float]] = None) -> str:
+    """
+    从 data 中按权重随机返回一条。
+    若 weights 为 None，则所有元素权重默认为 1。
+    """
+    if weights is None:
+        weights = [1.0] * len(data)
+
+    if len(data) != len(weights):
+        raise ValueError("data 和 weights 长度必须相等")
+
+    # 计算累计权重区间
+    total = 0.0
+    acc = []
+    for w in weights:
+        total += w
+        acc.append(total)
+
+    if total <= 0:
+        raise ValueError("总权重必须大于 0")
+
+    # 随机落点
+    r = random.random() * total
+    # 二分查找落点所在的区间
+    left, right = 0, len(acc) - 1
+    while left < right:
+        mid = (left + right) // 2
+        if r < acc[mid]:
+            right = mid
+        else:
+            left = mid + 1
+    return data[left]
+
+class BaseMain():
+    """基础主程序类"""
+    
+    def __init__(self):
+        """初始化基础主程序"""
+        self.easter_egg()
+    
+    def easter_egg(self):
+        # 彩蛋
+        init()
+        items = ["多年以后，面对AI行刑队，张三将会回想起他2023年在会议上讨论人工智能的那个下午", 
+             "你知道吗？诺狐的耳朵很软，很好rua", 
+             "喵喵~你的麦麦被猫娘入侵了喵~"]
+        w = [10, 5, 2]
+        text = weighted_choice(items, w)
+        rainbow_colors = [Fore.RED, Fore.YELLOW, Fore.GREEN, Fore.CYAN, Fore.BLUE, Fore.MAGENTA]
+        rainbow_text = ""
+        for i, char in enumerate(text):
+            rainbow_text += rainbow_colors[i % len(rainbow_colors)] + char
+        egg.info(rainbow_text)