Add design system, audit sections, apply global classes

Design system (design/):
- bcw-css-variables.json: color, spacing (--space-xs→2xl), typography (--h1→h6, --text-sm→xl)
- bcw-color-palette.json: named swatches referencing CSS variables
- bcw-global-classes.json: section-container, section-header, col-3, col-4, features-container, footer-sub-section
- design.md: full variable reference and usage guide

Templates:
- features-3col + features-4col: add global_classes embed + _cssGlobalClasses references
- All headers + footers: apply var(--color-primary) background to section elements
- footer-columns: add footer-sub-section class to column containers
- Remove content-image-left (duplicate of content-image-right with children reversed)
- testimonials: gap tweak 12px → 15px on card containers

Repo hygiene:
- Add .gitignore (Updated_Sections/)
- Clear Updated_Sections staging folder

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

design/bcw-global-classes.json

@@ -0,0 +1,74 @@
+[
+  {
+    "id": "features-container",
+    "name": "features-container",
+    "settings": {
+      "_typography": {
+        "text-align": "center"
+      },
+      "_rowGap": "10px"
+    },
+    "modified": 1772146285,
+    "user_id": 2
+  },
+  {
+    "id": "footer-sub-section",
+    "name": "footer-sub-section",
+    "settings": {
+      "_rowGap": "15px"
+    },
+    "modified": 1772146505,
+    "user_id": 2
+  },
+  {
+    "id": "section-container",
+    "name": "section-container",
+    "settings": {
+      "_direction": "column",
+      "_gap": "40px",
+      "_margin": {
+        "top": "15",
+        "bottom": "15"
+      }
+    },
+    "modified": 1772146505,
+    "user_id": 2
+  },
+  {
+    "id": "section-header",
+    "name": "section-header",
+    "settings": {
+      "_direction": "column",
+      "_alignItems": "center",
+      "_gap": "16px"
+    },
+    "modified": 1772146505,
+    "user_id": 2
+  },
+  {
+    "id": "col-3",
+    "name": "col-3",
+    "settings": {
+      "_direction": "row",
+      "_alignItems": "flex-start",
+      "_justifyContent": "center",
+      "_gap": "32px",
+      "_rowGap:mobile_portrait": "15px"
+    },
+    "modified": 1772146505,
+    "user_id": 2
+  },
+  {
+    "id": "col-4",
+    "name": "col-4",
+    "settings": {
+      "_direction": "row",
+      "_alignItems": "flex-start",
+      "_justifyContent": "center",
+      "_gap": "24px",
+      "_rowGap:mobile_portrait": "15px"
+    },
+    "modified": 1772146505,
+    "user_id": 2
+  }
+]