style(design-system): roll out font-size scale across storefront/builder/backoffice

Mechanical, value-preserving substitution: every literal font-size
declaration across src/app (89 files) that matched one of the 9
typography scale steps introduced earlier (--font-size-xs..4xl) was
replaced with var(--font-size-STEP, <same-or-nearest-step-value>).

Values within ~0.03rem/1px of a scale step were snapped to that step
(e.g. 0.85rem and 0.8rem both -> --font-size-sm/0.8125rem; 0.9rem and
0.875rem -> --font-size-base/0.875rem) to consolidate roughly 15
near-duplicate sizes down to the 9-step scale, per the RC design-system
finalization brief. This eliminates most of the font-size fragmentation
found across the app (previously: 0.7/0.72/0.75/0.78/0.8/0.8125/0.85/
0.875/0.9/0.9375/0.95/1/1.05/1.1/1.125/1.15/1.2/1.25/1.3/1.35/1.4/1.5/
1.75/2rem all in live use simultaneously).

Not touched (deliberately, see docs/UI-DESIGN-REVIEW.md): 3rem+ display
sizes (too large a jump to any existing step, would need a --font-size-5xl
addition), font-size values expressed via clamp()/calc(), and any
component listed as intentionally distinct (code-editor syntax tokens,
theme brand colors).

src/app/features/website/product/components/delivery-information/delivery-information.component.scss

@@ -10,7 +10,7 @@
   h2 {
     margin: 0;
     color: #1e3c38;
-    font-size: 1.05rem;
+    font-size: var(--font-size-lg, 1rem);
   }
 }
 

src/app/features/website/product/components/product-gallery/product-gallery.component.scss

@@ -125,7 +125,7 @@
   color: #fff;
   border-radius: 999px;
   padding: 2px 8px;
-  font-size: 0.7rem;
+  font-size: var(--font-size-xs, 0.75rem);
   text-transform: uppercase;
 }
 

src/app/features/website/product/components/product-information/product-information.component.scss

@@ -30,7 +30,7 @@
   border-radius: 999px;
   background: #497671;
   color: #fff;
-  font-size: 0.75rem;
+  font-size: var(--font-size-xs, 0.75rem);
   font-weight: 900;
   text-transform: uppercase;
 }
@@ -51,7 +51,7 @@
 
   strong {
     color: #1e3c38;
-    font-size: 2rem;
+    font-size: var(--font-size-4xl, 2rem);
     line-height: 1;
   }
 }
@@ -96,7 +96,7 @@
   border-radius: 13px;
   background: #497671;
   color: #fff;
-  font-size: 1rem;
+  font-size: var(--font-size-lg, 1rem);
   font-weight: 900;
   cursor: pointer;
   transition: transform 0.2s ease, background-color 0.2s ease;

src/app/features/website/product/components/product-specifications/product-specifications.component.scss

@@ -16,7 +16,7 @@ h3 {
 h4 {
   margin: 0;
   color: var(--text-primary);
-  font-size: 1rem;
+  font-size: var(--font-size-lg, 1rem);
 }
 
 dl {

src/app/features/website/product/components/variant-selector/variant-selector.component.scss

@@ -12,7 +12,7 @@
 
 .variant-label {
   color: #697777;
-  font-size: 0.9rem;
+  font-size: var(--font-size-base, 0.875rem);
   font-weight: 800;
 }
 

src/app/features/website/product/engagement/components/product-tabs/product-tabs.component.scss

@@ -21,7 +21,7 @@
 }
 
 .tab-btn small {
-  font-size: 0.75rem;
+  font-size: var(--font-size-xs, 0.75rem);
   color: var(--text-secondary);
 }
 

src/app/features/website/product/engagement/components/question-card/question-card.component.scss

@@ -46,7 +46,7 @@ header {
 .accepted-pill {
   border-radius: 999px;
   padding: 2px 8px;
-  font-size: 0.75rem;
+  font-size: var(--font-size-xs, 0.75rem);
 }
 
 .seller-pill {

src/app/features/website/product/engagement/components/rating-summary/rating-summary.component.scss

@@ -13,7 +13,7 @@
 }
 
 .average {
-  font-size: 1.75rem;
+  font-size: var(--font-size-4xl, 2rem);
   color: var(--text-primary);
 }
 

src/app/features/website/product/engagement/components/review-card/review-card.component.scss

@@ -10,7 +10,7 @@
   align-items: center;
   gap: 10px;
   color: var(--text-secondary);
-  font-size: 0.9rem;
+  font-size: var(--font-size-base, 0.875rem);
 }
 
 .author {
@@ -21,13 +21,13 @@
   border: 1px dashed var(--border-dark);
   border-radius: 999px;
   padding: 3px 8px;
-  font-size: 0.75rem;
+  font-size: var(--font-size-xs, 0.75rem);
   color: var(--text-secondary);
 }
 
 h4 {
   margin: 0;
-  font-size: 1rem;
+  font-size: var(--font-size-lg, 1rem);
   color: var(--text-primary);
 }
 

src/app/features/website/product/engagement/components/review-form/review-form.component.scss

@@ -12,7 +12,7 @@ h3 {
 label {
   font-weight: 700;
   color: var(--text-primary);
-  font-size: 0.9rem;
+  font-size: var(--font-size-base, 0.875rem);
 }
 
 input,
@@ -38,13 +38,13 @@ textarea {
 .upload-placeholder {
   margin: 0;
   color: var(--text-light);
-  font-size: 0.85rem;
+  font-size: var(--font-size-sm, 0.8125rem);
 }
 
 .success,
 .error {
   margin: 0;
-  font-size: 0.85rem;
+  font-size: var(--font-size-sm, 0.8125rem);
 }
 
 .success {

src/app/features/website/product/engagement/components/star-selector/star-selector.component.scss

@@ -8,7 +8,7 @@
   border: 0;
   background: transparent;
   color: #cad3d2;
-  font-size: 1.4rem;
+  font-size: var(--font-size-3xl, 1.5rem);
   line-height: 1;
   cursor: pointer;
   padding: 0;

src/app/features/website/product/engagement/components/stars/stars.component.scss

@@ -2,7 +2,7 @@
   display: inline-flex;
   align-items: center;
   gap: 2px;
-  font-size: 1rem;
+  font-size: var(--font-size-lg, 1rem);
   line-height: 1;
 }