feat(i18n): enhance localization with new actions and descriptions

- Added new action translations for "assassinate", "attack", "breakthrough", "cultivate", "escape", and "self-heal" in English, Simplified Chinese, and Traditional Chinese.
- Included detailed descriptions and requirements for each action to improve gameplay clarity.
- Updated the translation extraction and compilation process to utilize the polib library for better handling of PO files.

tests/test_i18n_modules.py

@@ -0,0 +1,87 @@
+import os
+from pathlib import Path
+import pytest
+import polib
+from src.i18n import t, _get_locale_dir
+
+def test_i18n_modules_structure():
+    """
+    Test that the i18n modules structure is correct.
+    """
+    locale_dir = _get_locale_dir()
+    # Directory names use underscores (zh_CN), not hyphens (zh-CN)
+    languages = ["zh_CN", "en_US", "zh_TW"]
+    
+    for lang in languages:
+        lang_dir = locale_dir / lang
+        assert lang_dir.exists(), f"Language directory {lang} does not exist"
+        
+        modules_dir = lang_dir / "modules"
+        assert modules_dir.exists(), f"Modules directory for {lang} does not exist"
+        assert modules_dir.is_dir()
+        
+        # Check if there are .po files in modules
+        po_files = list(modules_dir.glob("*.po"))
+        assert len(po_files) > 0, f"No .po files found in {modules_dir}"
+        
+        # Check specific expected modules
+        expected_modules = ["battle.po", "action.po", "fortune.po"]
+        for mod in expected_modules:
+            assert (modules_dir / mod).exists(), f"Expected module {mod} missing in {lang}"
+
+def test_merged_messages_po_integrity():
+    """
+    Test that the merged messages.po file in LC_MESSAGES exists and contains entries from modules.
+    """
+    locale_dir = _get_locale_dir()
+    lang = "zh_CN" # Test with one language (underscore)
+    
+    lc_messages_dir = locale_dir / lang / "LC_MESSAGES"
+    messages_po_path = lc_messages_dir / "messages.po"
+    
+    assert messages_po_path.exists(), "Merged messages.po does not exist"
+    
+    merged_po = polib.pofile(str(messages_po_path))
+    assert len(merged_po) > 0, "Merged messages.po is empty"
+    
+    # Check a random key from a module (e.g., from battle.po)
+    # We know "attack_action_name" should be in action.po or battle.po
+    # Actually "attack_action_name" is in action.po
+    
+    found_attack = False
+    for entry in merged_po:
+        if entry.msgid == "attack_action_name":
+            found_attack = True
+            break
+            
+    assert found_attack, "Key 'attack_action_name' (from action.po) not found in merged messages.po"
+
+def test_translation_loading():
+    """
+    Test that translations are actually loaded and working.
+    """
+    # This relies on the force_chinese_language fixture in conftest.py if run in full suite,
+    # or we explicitly set it here.
+    from src.classes.language import language_manager
+    language_manager.set_language("zh-CN")
+    
+    # Test a known key
+    # "attack_action_name" -> "发起战斗"
+    assert t("attack_action_name") == "发起战斗"
+    
+    # Test a formatted string
+    # "{winner} defeated {loser}" -> "{winner} 战胜了 {loser}"
+    # Note: the translation might be different, let's check exact value from file or flexible match
+    res = t("{winner} defeated {loser}", winner="A", loser="B")
+    assert "战胜了" in res
+
+def test_split_po_script_exists():
+    """
+    Ensure the maintenance scripts exist.
+    """
+    root = Path(__file__).parent.parent
+    split_script = root / "tools" / "i18n" / "split_po.py"
+    build_script = root / "tools" / "i18n" / "build_mo.py"
+    
+    assert split_script.exists()
+    assert build_script.exists()