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>

src/gui/pages/1_Deduplicator.py

@@ -54,7 +54,7 @@ for key, default in _DEFAULTS.items():
 # Header
 # ---------------------------------------------------------------------------
 
-st.title("🔍 Deduplicator")
+st.title("🔍 Find Duplicates")
 st.caption("Find and remove duplicate rows in CSV, delimited text, and Excel files.")
 
 
@@ -363,5 +363,5 @@ else:
 st.divider()
 st.caption(
     "Runs locally. Your data never leaves this computer. "
-    "| DataTools Deduplicator v3.0"
+    "| DataTools v3.0"
 )