feat: Forge design system app-wide + Stacks i18n

Promotes the Forge visual language from the Stacks feature into a
global design system used across the app:

- app.css: Forge utilities (dot-grid backdrop, eyebrow, ember,
  display/lede, status pills, stat grid, panels, registration
  marks, alert, terminal, buttons). CSS variables alias the forge
  display font to the app's standard sans stack (Inter, now
  properly self-hosted via @fontsource/inter).
- +layout.svelte: reskinned sidebar brand, active nav rail,
  mobile top bar, global h1/h2 typography overrides, main dot-grid
  backdrop.
- Shared components reskinned: EmptyState (breathing-ember empty
  mark), StatusBadge (mono pills with pulse), ConfirmDialog
  (registration marks + forge buttons).
- Dashboard (+page.svelte): ForgeHero header, forge-stat-grid,
  Instrument-style section titles with accent.
- New ForgeHero component for reusable hero headers.

Stacks feature fully localized (EN + RU):
- 80+ keys under stacks.* covering list, new, detail, revisions,
  logs, errors, status labels, delete/rollback dialogs.
- Russian uses forge vocabulary (куются/наковальня/куём/etc).
- $t() wired through all three Stacks pages.

web/package.json

@@ -22,6 +22,7 @@
   "type": "module",
   "dependencies": {
     "@fontsource/instrument-serif": "^5.2.8",
+    "@fontsource/inter": "^5.2.8",
     "@fontsource/jetbrains-mono": "^5.2.8"
   }
 }