feat(gui): sidebar sections + non-technical tool labels

Sidebar nav now groups tools under Data Review / Data Cleaners /
Transformations / Automations via st.navigation, replacing the flat
auto-discovered list. Tool display names switch to action-first
phrasing (Find Duplicates, Fix Missing Values, Find Unusual Values,
Standardize Formats, Clean Text, Quality Check, Map Columns, Combine
Files, Automated Workflows) in EN + ES packs and on each page's H1.

The Data Cleaners section follows the requested order: Missing
Values → Outliers → Text Cleaner → Format Standardizer → Deduplicator
→ Quality Check. (Text Cleaner kept inside cleaners since the request
didn't list it but the tool still ships.) Registry now carries a
section field; helpers added: tools_in_section(), section_label().

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/gui/test_workflows.py

@@ -78,7 +78,7 @@ class TestTextCleanerWorkflow:
         app.run()
         assert not app.exception
         text = collected_text(app)
-        assert "Text Cleaner" in text
+        assert "Clean Text" in text
 
     def test_preview_or_clean_button_present(self, app_factory, small_csv_bytes):
         """The text cleaner ships a primary action (label varies by
@@ -106,7 +106,7 @@ class TestFormatStandardizerWorkflow:
         app.run()
         assert not app.exception
         text = collected_text(app)
-        assert "Format Standardizer" in text
+        assert "Standardize Formats" in text
 
 
 # ---------------------------------------------------------------------------
@@ -148,7 +148,7 @@ class TestPipelineRunnerWorkflow:
         app.run()
         assert not app.exception
         text = collected_text(app)
-        assert "Pipeline" in text
+        assert "Automated Workflows" in text
 
 
 # ---------------------------------------------------------------------------
@@ -194,9 +194,9 @@ class TestReviewWorkflow:
 # ---------------------------------------------------------------------------
 
 @pytest.mark.parametrize("slug,name", [
-    ("6_Outlier_Detector", "Outlier"),
-    ("7_Multi_File_Merger", "Merger"),
-    ("8_Validator_Reporter", "Validator"),
+    ("6_Outlier_Detector", "Unusual Values"),
+    ("7_Multi_File_Merger", "Combine Files"),
+    ("8_Validator_Reporter", "Quality Check"),
 ])
 class TestComingSoonStubs:
     def test_stub_renders(self, app_factory, slug, name):