feat(branding): optional per-app banner replacing logo + name in header

A brand may ship a wide banner (logo + wordmark in one image) that
replaces the brand-kit logo + app-name pair in a standalone's header.
Events is the first consumer.

Banners are optional and resolve at build time, mirroring the existing
@brand-app-logo chain:

- resolveAppBanner(app?) checks per-standalone override first
  (branding/<dep>/icons/<app>/banner.{svg,png}) then the brand's primary
  banner (branding/<dep>/banner.{svg,png}); returns null when absent
  instead of throwing, so brands without a banner keep logo + name.
- brandAppBannerAliasEntry() always registers the @brand-app-banner
  alias (falling back to the logo) so the static import resolves; whether
  it renders is gated by the VITE_APP_BANNER build flag.
- EventsPage renders the banner when the flag is set, else logo + name.

Deployers override per-standalone without touching the component. SVG
banners must have their text outlined to paths (browsers lack designer
fonts) — documented in branding/README.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

vite.events.config.ts

@@ -8,9 +8,11 @@ import { visualizer } from 'rollup-plugin-visualizer'
 import {
   brand,
   brandAlias,
+  brandAppBannerAliasEntry,
   brandAppLogoAliasEntry,
   brandAssetsPlugin,
   brandManifestName,
+  resolveAppBanner,
 } from './vite-branding'
 
 /**
@@ -55,6 +57,12 @@ function eventsHtmlPlugin(): Plugin {
 const APP_NAME = brandManifestName()
 process.env.VITE_APP_NAME = APP_NAME
 
+// When the active brand ships a banner (wide logo+wordmark lockup), the
+// events header renders it in place of the logo + name pair. Surfaced as
+// a '1'/'' flag the component reads; the actual file comes through the
+// @brand-app-banner alias below. See branding/README.md.
+process.env.VITE_APP_BANNER = resolveAppBanner('events') ? '1' : ''
+
 export default defineConfig(({ mode }) => ({
   base: process.env.VITE_BASE_PATH || '/',
   // Per-app dep cache so concurrent dev servers don't race on .vite/deps
@@ -128,6 +136,7 @@ export default defineConfig(({ mode }) => ({
     // aliases without one shadowing the other.
     alias: [
       brandAppLogoAliasEntry('events'),
+      brandAppBannerAliasEntry('events'),
       ...Object.entries(brandAlias).map(([find, replacement]) => ({ find, replacement })),
       { find: '@', replacement: fileURLToPath(new URL('./src', import.meta.url)) },
     ],