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/tools_registry.py

@@ -1,9 +1,9 @@
 """Per-tool manifest registry.
 
-Single source of truth for what tools exist, their display strings, and
-the tier (which controls whether a tool ships in a given build SKU). The
-home-page sidebar consumes this list; future per-tool packaging will
-filter it via the ``tier`` field.
+Single source of truth for what tools exist, their display strings, the
+left-nav section they belong to, and the tier (which controls whether a
+tool ships in a given build SKU). The home-page sidebar consumes this
+list; future per-tool packaging will filter it via the ``tier`` field.
 
 Adding a tool: append one ``Tool`` entry. Page filenames must match the
 ``page_slug`` so Streamlit's automatic page discovery picks them up.
@@ -22,6 +22,10 @@ from typing import Literal
 
 Tier = Literal["core", "pro", "enterprise"]
 Status = Literal["Ready", "Coming Soon"]
+# Sidebar grouping. The Review gate is its own section; cleaners,
+# transformations, and automations group the tools by what the user is
+# trying to accomplish rather than by implementation detail.
+Section = Literal["review", "cleaners", "transformations", "automations"]
 
 
 @dataclass(frozen=True)
@@ -34,102 +38,127 @@ class Tool:
     description: str       # One-sentence card body.
     page_slug: str         # Streamlit page filename without ".py" (e.g. "1_Deduplicator").
     status: Status         # "Ready" or "Coming Soon" — drives the card badge color.
+    section: Section       # Sidebar group this tool belongs to.
     tier: Tier = "core"    # Build-time gating hook; every tool is "core" today.
 
 
+# Order in this list IS the order shown in each sidebar section, so
+# arranging it carefully matters: within "cleaners" we lead with the
+# operations a non-technical user is most likely to need (filling
+# blanks, flagging outliers) before progressing to format cleanup,
+# dedup, and the final quality report.
 TOOLS: list[Tool] = [
-    Tool(
-        tool_id="01_deduplicator",
-        icon="🔍",
-        name="Deduplicator",
-        description=(
-            "Fuzzy matching, normalization, survivor selection, and "
-            "interactive review."
-        ),
-        page_slug="1_Deduplicator",
-        status="Ready",
-    ),
-    Tool(
-        tool_id="02_text_cleaner",
-        icon="✂️",
-        name="Text Cleaner",
-        description=(
-            "Whitespace trim, multi-space collapse, Unicode normalization, "
-            "BOM and line-ending handling."
-        ),
-        page_slug="2_Text_Cleaner",
-        status="Ready",
-    ),
-    Tool(
-        tool_id="03_format_standardizer",
-        icon="📐",
-        name="Format Standardizer",
-        description=(
-            "Standardize dates, currencies, names, phone numbers, and addresses."
-        ),
-        page_slug="3_Format_Standardizer",
-        status="Ready",
-    ),
     Tool(
         tool_id="04_missing_handler",
         icon="🕳️",
-        name="Missing Value Handler",
+        name="Fix Missing Values",
         description=(
             "Detect disguised nulls, missingness analysis, and imputation strategies."
         ),
         page_slug="4_Missing_Values",
         status="Ready",
-    ),
-    Tool(
-        tool_id="05_column_mapper",
-        icon="🗂️",
-        name="Column Mapper",
-        description="Rename columns, enforce a target schema, and coerce types.",
-        page_slug="5_Column_Mapper",
-        status="Ready",
+        section="cleaners",
     ),
     Tool(
         tool_id="06_outlier_detector",
         icon="📊",
-        name="Outlier Detector",
+        name="Find Unusual Values",
         description=(
             "Z-score, IQR, and MAD detection with domain-rule violations and "
             "winsorization."
         ),
         page_slug="6_Outlier_Detector",
         status="Coming Soon",
+        section="cleaners",
     ),
     Tool(
-        tool_id="07_multi_file_merger",
-        icon="📎",
-        name="Multi-File Merger",
-        description="Combine multiple CSV/Excel files with schema alignment.",
-        page_slug="7_Multi_File_Merger",
-        status="Coming Soon",
+        tool_id="02_text_cleaner",
+        icon="✂️",
+        name="Clean Text",
+        description=(
+            "Whitespace trim, multi-space collapse, Unicode normalization, "
+            "BOM and line-ending handling."
+        ),
+        page_slug="2_Text_Cleaner",
+        status="Ready",
+        section="cleaners",
+    ),
+    Tool(
+        tool_id="03_format_standardizer",
+        icon="📐",
+        name="Standardize Formats",
+        description=(
+            "Standardize dates, currencies, names, phone numbers, and addresses."
+        ),
+        page_slug="3_Format_Standardizer",
+        status="Ready",
+        section="cleaners",
+    ),
+    Tool(
+        tool_id="01_deduplicator",
+        icon="🔍",
+        name="Find Duplicates",
+        description=(
+            "Fuzzy matching, normalization, survivor selection, and "
+            "interactive review."
+        ),
+        page_slug="1_Deduplicator",
+        status="Ready",
+        section="cleaners",
     ),
     Tool(
         tool_id="08_validator_reporter",
         icon="✅",
-        name="Validator & Reporter",
+        name="Quality Check",
         description=(
             "Validate against rules and generate PDF/Excel quality reports."
         ),
         page_slug="8_Validator_Reporter",
         status="Coming Soon",
+        section="cleaners",
+    ),
+    Tool(
+        tool_id="05_column_mapper",
+        icon="🗂️",
+        name="Map Columns",
+        description="Rename columns, enforce a target schema, and coerce types.",
+        page_slug="5_Column_Mapper",
+        status="Ready",
+        section="transformations",
+    ),
+    Tool(
+        tool_id="07_multi_file_merger",
+        icon="📎",
+        name="Combine Files",
+        description="Combine multiple CSV/Excel files with schema alignment.",
+        page_slug="7_Multi_File_Merger",
+        status="Coming Soon",
+        section="transformations",
     ),
     Tool(
         tool_id="09_pipeline_runner",
         icon="⚙️",
-        name="Pipeline Runner",
+        name="Automated Workflows",
         description=(
             "Chain tools in recommended order and pass output between steps."
         ),
         page_slug="9_Pipeline_Runner",
         status="Ready",
+        section="automations",
     ),
 ]
 
 
+# Display labels for each sidebar section. Kept here so i18n falls back
+# to a sensible English string if a translation pack is missing the key.
+SECTION_LABELS: dict[Section, str] = {
+    "review": "Data Review",
+    "cleaners": "Data Cleaners",
+    "transformations": "Transformations",
+    "automations": "Automations",
+}
+
+
 def tools_for_tier(*tiers: Tier) -> list[Tool]:
     """Subset filter for build-time slicing.
 
@@ -142,6 +171,11 @@ def tools_for_tier(*tiers: Tier) -> list[Tool]:
     return [t for t in TOOLS if t.tier in keep]
 
 
+def tools_in_section(section: Section) -> list[Tool]:
+    """Return the tools in *section*, preserving registry order."""
+    return [t for t in TOOLS if t.section == section]
+
+
 def tool_by_id(tool_id: str) -> Tool | None:
     return next((t for t in TOOLS if t.tool_id == tool_id), None)
 
@@ -167,3 +201,12 @@ def tool_description(tool_id: str) -> str:
     fallback = tool.description if tool else ""
     translated = _t(f"tools.{tool_id}.description")
     return translated if translated != f"tools.{tool_id}.description" else fallback
+
+
+def section_label(section: Section) -> str:
+    """Return the localized sidebar section header."""
+    from src.i18n import t as _t
+    fallback = SECTION_LABELS[section]
+    key = f"nav.section_{section}"
+    translated = _t(key)
+    return translated if translated != key else fallback