Various build shenenigans (#5)

This PR extends the build pipeline of the www service to support
locale-prefixed static builds (EN/RU) with build-time SSG output
injection, while also refactoring UI typography to a tokenized Tailwind
v4 @theme-driven approach.

Changes:

- Add build-time SSG plugin to @ermnvldmr/rsbuild-config and wire
multi-locale builds (/en/, /ru/) into services/www.
- Introduce new @ermnvldmr/i18n package (locale constants, path helpers,
keysets, pluralization) and apply it to www navigation/text.
- Refactor ui typography to a shared getTypographyClassNames utility +
Tailwind token definitions, with stl/cn updated for correct
Tailwind-merge behavior.

packages/ui/src/components/Breadcrumbs/Breadcrumbs.test.tsx

@@ -41,7 +41,7 @@ describe('components/Breadcrumbs', () => {
       </Breadcrumbs>
     );
     const link = screen.getByRole('link', { name: 'Test Link' });
-    expect(link).toHaveAttribute('href', '/test-url');
+    expect(link).toHaveAttribute('href', '/en/test-url');
   });
 
   it('supports onClick on Item', () => {

packages/ui/src/components/Breadcrumbs/Breadcrumbs.tsx

@@ -1,3 +1,4 @@
+import { localePath } from '@ermnvldmr/i18n';
 import { cn } from '@ermnvldmr/stl';
 import { ChevronRight } from 'lucide-react';
 import React, { memo } from 'react';
@@ -56,7 +57,8 @@ const BreadcrumbsItem = memo(function BreadcrumbsItem({
   onClick,
   'data-testid': testId,
 }: BreadcrumbsItemProps) {
-  const isClickable = !!(href ?? onClick);
+  const resolvedHref = localePath(href);
+  const isClickable = !!(resolvedHref ?? onClick);
 
   return (
     <li
@@ -69,13 +71,13 @@ const BreadcrumbsItem = memo(function BreadcrumbsItem({
       data-testid={testId}
     >
       <Text
-        as={href ? 'a' : onClick ? 'button' : 'span'}
+        as={resolvedHref ? 'a' : onClick ? 'button' : 'span'}
         className={cn(
           'transition-all duration-200',
           !isCurrent && 'group-hover:text-[var(--rb-text)] group-hover:underline underline-offset-4'
         )}
         color={isCurrent ? 'default' : 'muted'}
-        href={href}
+        href={resolvedHref}
         size="m"
         type="label"
         onClick={onClick}