docs: add nginx tenant onboarding template and backend handoff doc

Adds a copy-paste server block template for onboarding a new marketplace
domain, and a Sprint 16 backend handoff doc covering the still-missing
draft/publish persistence endpoints, server-side validation expectations,
and the slug/route inconsistency in static-page data.

docs/Backend-Handoff-Sprint16.md

@@ -0,0 +1,90 @@
+# Backend Handoff — Sprint 16 (Project Editor)
+
+For backend devs picking up work after the Sprint 16 frontend editor. Frontend
+is done; this documents what backend still needs to build for the editor to
+be real (not just an in-browser demo).
+
+## What exists today (frontend-only)
+
+The Project Editor (`/edit/:section`, or `/{lang}/edit/:section`) edits the
+same `BootstrapConfig` the storefront consumes — no parallel model. Today:
+
+- **Load:** `GET /bootstrap` (existing, tenant resolved by request host).
+- **Save:** in-memory only. `ProjectEditorFacade.save()` just snapshots the
+  current draft as "last saved" in the browser tab. Nothing is persisted.
+  Reload the page, or open the editor in another tab/browser, and it's gone.
+- **Publish:** `ProjectEditorFacade.publish()` applies the bootstrap
+  in-memory via `PlatformRuntimeService.reloadFromBootstrap` (for live
+  preview) and flips a local `status` flag to `'published'`. It does not
+  call any backend endpoint. Nothing is persisted.
+
+This is fine for demoing the editor UI to one person in one browser tab. It
+is not usable as a real per-tenant admin panel yet — that's this handoff.
+
+## Endpoints backend needs to add
+
+None of these exist yet. Suggested shapes (adjust to match your existing API
+conventions — these are contracts, not prescriptions):
+
+```
+GET  /builder/bootstrap/draft
+  -> returns the tenant's current draft BootstrapConfig (may differ from
+     the published one). 404/empty if no draft exists yet (draft = published).
+
+PUT  /builder/bootstrap/draft
+  body: BootstrapConfig
+  -> persists the draft for this tenant. Does not affect what GET /bootstrap
+     (storefront-facing) returns.
+
+POST /builder/bootstrap/publish
+  body: BootstrapConfig  (or no body, if publish always promotes the
+        current stored draft)
+  -> validates, then makes this BootstrapConfig the one GET /bootstrap
+     returns for this tenant. This is the only endpoint that affects the
+     live storefront.
+
+POST /builder/bootstrap/validate   (optional — validation already runs
+                                     client-side via ProjectValidator, but a
+                                     server-side check prevents a stale/
+                                     bypassed client from publishing garbage)
+  body: BootstrapConfig
+  -> returns the same shape as the client's ProjectValidationIssue[]:
+     { code: string, message: string }[]
+```
+
+Tenant identity: same as every other endpoint in this platform — resolved by
+request host, not a `projectId` path param (see `docs/backend-platform/
+tenant-resolution.md`). There is no multi-project-per-domain concept; each
+domain is one tenant with one draft and one published bootstrap.
+
+## What the frontend already validates (don't duplicate logic, just enforce it)
+
+`ProjectValidator` (`src/app/features/project-editor/services/
+project-validator.service.ts`) blocks Publish client-side on:
+missing `branding.logoUrl`, empty `localization.supportedLocales`, invalid
+`tenant.websiteBaseUrl` (must be `http(s)://...`), duplicate static-page
+identifiers (slug, falling back to route), empty homepage sections, a
+homepage widget with no `type`, duplicate header nav links, and any
+non-hex-string `theme.palette` value. A malicious or buggy client could
+bypass all of this — if `POST /builder/bootstrap/publish` is meant to be a
+trust boundary, re-run equivalent checks server-side before accepting.
+
+## Static pages: `slug` vs `route`
+
+Heads up for whoever owns `StaticPageConfig`: the model requires `slug:
+string`, but at least one real bootstrap in this repo
+(`src/assets/mock/bootstrap/bootstrap.json`) only populates `route` (e.g.
+`/about-us`) and leaves `slug` undefined. The frontend's duplicate-detection
+was patched to fall back to `route` when `slug` is empty
+(`project-validator.service.ts`), but the underlying data inconsistency is
+still there. Worth deciding whether `slug` should be backend-required/
+auto-derived from `route` going forward, so both frontend and backend agree
+on one source of truth.
+
+## Not in scope for this handoff (already tracked separately)
+
+- Separate admin app/deployment (`admin.<domain>` subdomain) — storefront and
+  editor still ship in one Angular build today.
+- A pre-existing, unrelated crash in `ContentPageService.normalizeSlug`
+  against legacy-shaped static-page fixture data (frontend bug, not a
+  backend concern).

nginx.conf

@@ -94,3 +94,57 @@ server {
     add_header X-XSS-Protection "1; mode=block" always;
     add_header Referrer-Policy "strict-origin-when-cross-origin" always;
 }
+
+# Template for onboarding a new marketplace tenant.
+# Replace NEWMARKETPLACE.EXAMPLE.COM, /var/www/newmarketplace, and the
+# api.newmarketplace.example.com:443 proxy target with the real values,
+# then rename this block's server_name/root before deploying.
+server {
+    listen 80;
+    server_name newmarketplace.example.com www.newmarketplace.example.com;
+
+    root /var/www/newmarketplace/browser;
+    index index.html;
+
+    # Angular routing - serve index.html for all routes (client-side router
+    # handles /edit, /:lang/edit/:section, etc. once index.html is served)
+    location / {
+        try_files $uri $uri/ /index.html =404;
+    }
+
+    # Proxy API calls to backend
+    location /api {
+        proxy_pass https://api.newmarketplace.example.com:443;
+        proxy_set_header Host api.newmarketplace.example.com;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        rewrite ^/api(/.*)$ $1 break;
+        proxy_ssl_verify off;
+    }
+
+    # Static assets caching
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+        try_files $uri =404;
+    }
+
+    # Don't cache index.html
+    location = /index.html {
+        add_header Cache-Control "no-cache, no-store, must-revalidate";
+        add_header Pragma "no-cache";
+        add_header Expires "0";
+    }
+
+    gzip on;
+    gzip_vary on;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript image/svg+xml;
+    gzip_min_length 1000;
+
+    add_header X-Frame-Options "SAMEORIGIN" always;
+    add_header X-Content-Type-Options "nosniff" always;
+    add_header X-XSS-Protection "1; mode=block" always;
+    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+}