test(wave168): transition_presets转场预设 +35测

- TransitionPreset数据类：最小创建/默认值/完整参数/frozen不可变/tags独立
- 预设库：非空/ID唯一/必填字段/6个分类存在/转场none/时长min<=default<=max/总数
- get_transition_preset：存在ID/不存在/空串/大小写敏感/返回类型
- list_transition_presets：无筛选/分类筛选(basic/fade/slide)/无效分类
  + 关键词搜索(名称/标签/描述)+组合筛选/空关键词/返回类型
- get_default_transition：返回类型/是none/零时长/硬切

tests/unit/domain/test_transition_presets.py

@@ -0,0 +1,240 @@
+"""transition_presets 单元测试 - wave168
+
+覆盖：
+- TransitionPreset 数据类（frozen/默认值/字段）
+- TRANSITION_PRESET_LIBRARY 预设库（数量/分类/ID唯一性）
+- get_transition_preset 按ID获取
+- list_transition_presets 筛选列表（分类/关键词）
+- get_default_transition 默认转场
+"""
+
+import dataclasses
+
+import pytest
+
+from packages.domain.transition_presets import (
+    TRANSITION_PRESET_LIBRARY,
+    TransitionPreset,
+    get_default_transition,
+    get_transition_preset,
+    list_transition_presets,
+)
+
+# ============================================================
+# TransitionPreset 数据类
+# ============================================================
+
+
+class TestTransitionPresetDataclass:
+    def test_minimal_creation(self):
+        p = TransitionPreset(id="test", name="Test", category="basic")
+        assert p.id == "test"
+        assert p.name == "Test"
+        assert p.category == "basic"
+
+    def test_default_values(self):
+        p = TransitionPreset(id="t", name="T", category="basic")
+        assert p.description == ""
+        assert p.tags == []
+        assert p.transition == "fade"
+        assert p.default_duration == 0.5
+        assert p.min_duration == 0.1
+        assert p.max_duration == 3.0
+        assert p.has_custom_params is False
+
+    def test_full_creation(self):
+        p = TransitionPreset(
+            id="full",
+            name="Full",
+            category="fade",
+            description="test desc",
+            tags=["tag1", "tag2"],
+            transition="fadeblack",
+            default_duration=1.0,
+            min_duration=0.2,
+            max_duration=5.0,
+            has_custom_params=True,
+        )
+        assert p.description == "test desc"
+        assert p.tags == ["tag1", "tag2"]
+        assert p.transition == "fadeblack"
+        assert p.default_duration == 1.0
+        assert p.min_duration == 0.2
+        assert p.max_duration == 5.0
+        assert p.has_custom_params is True
+
+    def test_frozen_immutable(self):
+        p = TransitionPreset(id="t", name="T", category="basic")
+        with pytest.raises(dataclasses.FrozenInstanceError):
+            p.name = "Changed"
+
+    def test_tags_default_new_list(self):
+        p1 = TransitionPreset(id="t1", name="T1", category="basic")
+        p2 = TransitionPreset(id="t2", name="T2", category="basic")
+        assert p1.tags is not p2.tags
+
+
+# ============================================================
+# TRANSITION_PRESET_LIBRARY 预设库
+# ============================================================
+
+
+class TestTransitionPresetLibrary:
+    def test_library_not_empty(self):
+        assert len(TRANSITION_PRESET_LIBRARY) > 0
+
+    def test_all_ids_unique(self):
+        ids = [p.id for p in TRANSITION_PRESET_LIBRARY]
+        assert len(ids) == len(set(ids))
+
+    def test_all_have_required_fields(self):
+        for p in TRANSITION_PRESET_LIBRARY:
+            assert p.id, f"缺少id: {p}"
+            assert p.name, f"缺少name: {p.id}"
+            assert p.category, f"缺少category: {p.id}"
+            assert p.transition, f"缺少transition: {p.id}"
+
+    def test_valid_categories(self):
+        valid = {"basic", "fade", "slide", "zoom", "warp", "special"}
+        for p in TRANSITION_PRESET_LIBRARY:
+            assert p.category in valid, f"无效分类: {p.id} -> {p.category}"
+
+    def test_basic_category_exists(self):
+        basics = [p for p in TRANSITION_PRESET_LIBRARY if p.category == "basic"]
+        assert len(basics) >= 1
+
+    def test_fade_category_exists(self):
+        fades = [p for p in TRANSITION_PRESET_LIBRARY if p.category == "fade"]
+        assert len(fades) >= 1
+
+    def test_transition_none_exists(self):
+        none_p = get_transition_preset("transition_none")
+        assert none_p is not None
+        assert none_p.transition == "none"
+        assert none_p.default_duration == 0.0
+
+    def test_duration_consistency(self):
+        # min <= default <= max
+        for p in TRANSITION_PRESET_LIBRARY:
+            assert p.min_duration <= p.default_duration, f"{p.id}: min > default"
+            assert p.default_duration <= p.max_duration, f"{p.id}: default > max"
+
+    def test_total_count(self):
+        # 至少有10个转场预设
+        assert len(TRANSITION_PRESET_LIBRARY) >= 10
+
+
+# ============================================================
+# get_transition_preset
+# ============================================================
+
+
+class TestGetTransitionPreset:
+    def test_existing_id(self):
+        p = get_transition_preset("transition_none")
+        assert p is not None
+        assert p.id == "transition_none"
+        assert p.name == "无转场"
+
+    def test_nonexistent_id(self):
+        assert get_transition_preset("nonexistent") is None
+
+    def test_empty_id(self):
+        assert get_transition_preset("") is None
+
+    def test_case_sensitive(self):
+        assert get_transition_preset("Transition_None") is None
+
+    def test_returns_preset_object(self):
+        p = get_transition_preset("transition_none")
+        assert isinstance(p, TransitionPreset)
+
+
+# ============================================================
+# list_transition_presets
+# ============================================================
+
+
+class TestListTransitionPresets:
+    def test_no_filters_returns_all(self):
+        result = list_transition_presets()
+        assert len(result) == len(TRANSITION_PRESET_LIBRARY)
+
+    def test_filter_by_category_basic(self):
+        result = list_transition_presets(category="basic")
+        assert len(result) > 0
+        for p in result:
+            assert p.category == "basic"
+
+    def test_filter_by_category_fade(self):
+        result = list_transition_presets(category="fade")
+        for p in result:
+            assert p.category == "fade"
+
+    def test_filter_by_category_slide(self):
+        result = list_transition_presets(category="slide")
+        for p in result:
+            assert p.category == "slide"
+
+    def test_invalid_category_returns_empty(self):
+        result = list_transition_presets(category="nonexistent")
+        assert result == []
+
+    def test_keyword_search_name(self):
+        result = list_transition_presets(keyword="淡")
+        assert len(result) >= 1
+        names = [p.name for p in result]
+        assert any("淡" in n for n in names)
+
+    def test_keyword_search_tags(self):
+        result = list_transition_presets(keyword="硬切")
+        assert len(result) >= 1
+        found = any(any("硬切" in t for t in p.tags) or "硬切" in p.name for p in result)
+        assert found
+
+    def test_keyword_search_description(self):
+        # 搜索描述中的关键词
+        result = list_transition_presets(keyword="过渡")
+        assert isinstance(result, list)
+
+    def test_keyword_nonexistent_returns_empty(self):
+        result = list_transition_presets(keyword="zzz不存在的关键词zzz")
+        assert result == []
+
+    def test_category_and_keyword_combined(self):
+        result = list_transition_presets(category="fade", keyword="淡")
+        for p in result:
+            assert p.category == "fade"
+            assert "淡" in p.name or "淡" in p.description or any("淡" in t for t in p.tags)
+
+    def test_keyword_empty_returns_all(self):
+        result = list_transition_presets(keyword="")
+        assert len(result) == len(TRANSITION_PRESET_LIBRARY)
+
+    def test_returns_list_of_presets(self):
+        result = list_transition_presets()
+        for p in result:
+            assert isinstance(p, TransitionPreset)
+
+
+# ============================================================
+# get_default_transition
+# ============================================================
+
+
+class TestGetDefaultTransition:
+    def test_returns_preset(self):
+        p = get_default_transition()
+        assert isinstance(p, TransitionPreset)
+
+    def test_default_is_none(self):
+        p = get_default_transition()
+        assert p.id == "transition_none"
+
+    def test_default_has_zero_duration(self):
+        p = get_default_transition()
+        assert p.default_duration == 0.0
+
+    def test_default_is_hard_cut(self):
+        p = get_default_transition()
+        assert p.transition == "none"