Add MTG rules engine source files

backend/mtg_rules_engine/__init__.py

@@ -0,0 +1,39 @@
+"""
+Magic: The Gathering Rules Engine
+
+A comprehensive rules engine for validating and simulating Magic: The Gathering gameplay.
+Uses a hardcoded keyword database to ensure rule compliance during gameplay.
+
+Modules:
+    keywords: Hardcoded keyword database with all Magic keywords and their definitions
+    validator: Keyword validation and analysis utilities
+    engine: Core rules engine for card and action validation
+"""
+
+from .keywords import (
+    ABILITY_WORDS,
+    KEYWORD_ACTIONS,
+    KEYWORD_ABILITIES,
+    KEYWORD_VARIANTS,
+    get_all_keywords,
+    get_keyword_info,
+    is_valid_keyword,
+    get_keyword_type,
+)
+from .validator import KeywordValidator
+from .engine import RulesEngine
+
+__all__ = [
+    # Keyword data
+    "ABILITY_WORDS",
+    "KEYWORD_ACTIONS",
+    "KEYWORD_ABILITIES", 
+    "KEYWORD_VARIANTS",
+    "get_all_keywords",
+    "get_keyword_info",
+    "is_valid_keyword",
+    "get_keyword_type",
+    # Classes
+    "KeywordValidator",
+    "RulesEngine",
+]