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_lite_tier.py

@@ -40,9 +40,9 @@ def lite_license(monkeypatch, tmp_path):
 
 class TestLiteUnlockedPages:
     @pytest.mark.parametrize("slug,signal", [
-        ("1_Deduplicator", "Deduplicator"),
-        ("2_Text_Cleaner", "Text Cleaner"),
-        ("3_Format_Standardizer", "Format Standardizer"),
+        ("1_Deduplicator", "Find Duplicates"),
+        ("2_Text_Cleaner", "Clean Text"),
+        ("3_Format_Standardizer", "Standardize Formats"),
     ])
     def test_unlocked_pages_render_body(
         self, lite_license, app_factory, slug, signal, small_csv_bytes,