docs(branding): brand kit contract + CLAUDE.md section

branding/README.md is the deployer contract:
- Directory layout, source format constraints (SVG > PNG ≥ 1024),
  brand.json schema, per-standalone override resolution order
- BRAND_DIR / BRAND_APP usage, generator pipeline walkthrough
- Pointer to issue #95 + the NixOS Phase 2 integration

webapp CLAUDE.md gains a Brand Kit section describing the moving
parts (vite-branding.ts, @brand alias, brandAssetsPlugin,
public/icons/ gitignore, per-app override path) so future sessions
on this repo know the convention without grepping.

Adds BRAND_DIR / BRAND_APP to the Environment Variables example.

Workspace ~/dev/CLAUDE.md note about "brand changes don't need
flake.lock bump" deferred to Phase 2 (server-deploy migration) —
that's when the workflow becomes reality.

Part of aiolabs/webapp#95.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -712,8 +712,60 @@ VITE_ADMIN_PUBKEYS='["pubkey1","pubkey2"]'
 
 # Optional: Disable WebSocket if needed
 VITE_WEBSOCKET_ENABLED=true
+
+# Brand kit override (defaults to ./branding/default)
+BRAND_DIR=branding/cfaun
+
+# Per-standalone brand override (set by build pipeline, not directly)
+BRAND_APP=events
 ```
 
+## Brand kit (white-label PWA branding)
+
+The webapp ships a brand kit architecture so the hub + every standalone
+(events, wallet, chat, market, …) can be rebranded per deployment without
+forking the codebase. See `branding/README.md` for the deployer contract.
+
+**Single source of truth:** `branding/<dep>/` holds `logo.{svg,png}` +
+`brand.json`. `vite-branding.ts` reads brand.json and exposes a `@brand`
+import alias. `pwa-assets.config.ts` + `@vite-pwa/assets-generator` derive
+the full PWA icon set from the single logo source.
+
+**brand.json schema:** `{ name, shortName?, themeColor?, backgroundColor? }`
+— `name` drives the manifest. `themeColor`/`backgroundColor` are optional
+chrome overrides; when unset, each standalone's per-app accent applies.
+
+**In-app logo:** components reference `@brand/logo.png`. Active consumers:
+`Login.vue`, `LoginDemo.vue`, `AppSidebar.vue`, `MobileDrawer.vue`. The
+Vite alias resolves to the active brand dir at build time.
+
+**Generated icons:** `public/icons/` is gitignored. `brandAssetsPlugin()`
+(registered first in every `vite.*.config.ts`'s plugins[]) runs the
+generator once per build/dev start via `buildStart`. Outputs match the
+existing filename convention (`icon-192.png`, `icon-maskable-512.png`,
+…) so HTML `<link>` hrefs and VitePWA `manifest.icons` reference
+`/icons/<name>` consistently across all 9 configs.
+
+**Per-standalone override:** `branding/<dep>/icons/<app>/logo.{svg,png}`
+is checked before the brand's primary logo. The standalone build sets
+`BRAND_APP`; deployers just put files in the right place.
+
+**Switching brands:**
+```bash
+BRAND_DIR=branding/cfaun pnpm build:events
+```
+
+**Adding a new in-app logo consumer:** use `<img src="@brand/logo.png">`
+instead of `@/assets/logo.png`. The latter still works for non-brand
+assets (`@/assets/bitcoin.svg`, etc.) — it's only the logo that moved.
+
+**NixOS deployment:** brand directories will eventually live in
+`deploy/server-deploy/hosts/<host>/branding/`, with each host's
+`services/webapp.nix` calling `inputs.webapp.lib.mkWebapp { brandDir =
+./../branding; }`. `flake.nix` exposing `lib.mkWebapp` is a follow-up
+to this PR. Until it lands, server-deploy continues to build webapp
+through its existing path. See aiolabs/server-deploy#8.
+
 ## Payment Rails Pattern
 
 Shared primitives for modules that mix Lightning + fiat (and, future,