fix(performance): use simple height estimation instead of PIL rendering

- Replace estimate_block_height (PIL-based) with estimate_simple_height (word wrap)
- Update viewport filter tests to match new height-based filtering (~4 items vs 24)
- Fix CI task duplication in mise.toml (remove redundant depends)

Closes #38
Closes #36

tests/test_app.py

@@ -18,7 +18,7 @@ class TestMain:
 
     def test_main_calls_run_pipeline_mode_with_default_preset(self):
         """main() runs default preset (demo) when no args provided."""
-        with patch("engine.app.run_pipeline_mode") as mock_run:
+        with patch("engine.app.main.run_pipeline_mode") as mock_run:
             sys.argv = ["mainline.py"]
             main()
             mock_run.assert_called_once_with("demo")
@@ -26,12 +26,11 @@ class TestMain:
     def test_main_calls_run_pipeline_mode_with_config_preset(self):
         """main() uses PRESET from config if set."""
         with (
-            patch("engine.app.config") as mock_config,
-            patch("engine.app.run_pipeline_mode") as mock_run,
+            patch("engine.config.PIPELINE_DIAGRAM", False),
+            patch("engine.config.PRESET", "gallery-sources"),
+            patch("engine.config.PIPELINE_MODE", False),
+            patch("engine.app.main.run_pipeline_mode") as mock_run,
         ):
-            mock_config.PIPELINE_DIAGRAM = False
-            mock_config.PRESET = "gallery-sources"
-            mock_config.PIPELINE_MODE = False
             sys.argv = ["mainline.py"]
             main()
             mock_run.assert_called_once_with("gallery-sources")
@@ -39,12 +38,11 @@ class TestMain:
     def test_main_exits_on_unknown_preset(self):
         """main() exits with error for unknown preset."""
         with (
-            patch("engine.app.config") as mock_config,
-            patch("engine.app.list_presets", return_value=["demo", "poetry"]),
+            patch("engine.config.PIPELINE_DIAGRAM", False),
+            patch("engine.config.PRESET", "nonexistent"),
+            patch("engine.config.PIPELINE_MODE", False),
+            patch("engine.pipeline.list_presets", return_value=["demo", "poetry"]),
         ):
-            mock_config.PIPELINE_DIAGRAM = False
-            mock_config.PRESET = "nonexistent"
-            mock_config.PIPELINE_MODE = False
             sys.argv = ["mainline.py"]
             with pytest.raises(SystemExit) as exc_info:
                 main()
@@ -70,9 +68,11 @@ class TestRunPipelineMode:
     def test_run_pipeline_mode_exits_when_no_content_available(self):
         """run_pipeline_mode() exits if no content can be fetched."""
         with (
-            patch("engine.app.load_cache", return_value=None),
-            patch("engine.app.fetch_all", return_value=([], None, None)),
-            patch("engine.app.effects_plugins"),
+            patch("engine.app.pipeline_runner.load_cache", return_value=None),
+            patch(
+                "engine.app.pipeline_runner.fetch_all", return_value=([], None, None)
+            ),
+            patch("engine.effects.plugins.discover_plugins"),
             pytest.raises(SystemExit) as exc_info,
         ):
             run_pipeline_mode("demo")
@@ -82,9 +82,11 @@ class TestRunPipelineMode:
         """run_pipeline_mode() uses cached content if available."""
         cached = ["cached_item"]
         with (
-            patch("engine.app.load_cache", return_value=cached) as mock_load,
-            patch("engine.app.fetch_all") as mock_fetch,
-            patch("engine.app.DisplayRegistry.create") as mock_create,
+            patch(
+                "engine.app.pipeline_runner.load_cache", return_value=cached
+            ) as mock_load,
+            patch("engine.app.pipeline_runner.fetch_all") as mock_fetch,
+            patch("engine.app.pipeline_runner.DisplayRegistry.create") as mock_create,
         ):
             mock_display = Mock()
             mock_display.init = Mock()
@@ -155,12 +157,13 @@ class TestRunPipelineMode:
     def test_run_pipeline_mode_fetches_poetry_for_poetry_source(self):
         """run_pipeline_mode() fetches poetry for poetry preset."""
         with (
-            patch("engine.app.load_cache", return_value=None),
+            patch("engine.app.pipeline_runner.load_cache", return_value=None),
             patch(
-                "engine.app.fetch_poetry", return_value=(["poem"], None, None)
+                "engine.app.pipeline_runner.fetch_poetry",
+                return_value=(["poem"], None, None),
             ) as mock_fetch_poetry,
-            patch("engine.app.fetch_all") as mock_fetch_all,
-            patch("engine.app.DisplayRegistry.create") as mock_create,
+            patch("engine.app.pipeline_runner.fetch_all") as mock_fetch_all,
+            patch("engine.app.pipeline_runner.DisplayRegistry.create") as mock_create,
         ):
             mock_display = Mock()
             mock_display.init = Mock()
@@ -183,9 +186,9 @@ class TestRunPipelineMode:
     def test_run_pipeline_mode_discovers_effect_plugins(self):
         """run_pipeline_mode() discovers available effect plugins."""
         with (
-            patch("engine.app.load_cache", return_value=["item"]),
-            patch("engine.app.effects_plugins") as mock_effects,
-            patch("engine.app.DisplayRegistry.create") as mock_create,
+            patch("engine.app.pipeline_runner.load_cache", return_value=["item"]),
+            patch("engine.effects.plugins.discover_plugins") as mock_discover,
+            patch("engine.app.pipeline_runner.DisplayRegistry.create") as mock_create,
         ):
             mock_display = Mock()
             mock_display.init = Mock()
@@ -202,4 +205,4 @@ class TestRunPipelineMode:
                 pass
 
             # Verify effects_plugins.discover_plugins was called
-            mock_effects.discover_plugins.assert_called_once()
+            mock_discover.assert_called_once()