feat: public v1 API + token management + OpenAPI docs (#322)

Adds a long-lived bearer-token mechanism + scoped REST surface designed
for n8n-style automation: create a gallery, upload photos, fetch the
share URL — all via documented HTTPS endpoints instead of poking at the
admin UI's internal routes.

API
- Migration 081 adds `api_tokens` (hashed_token, scopes, owner FK,
  last_used/expires/revoked timestamps).
- New apiTokenAuth middleware: parses `Authorization: Bearer pp_live_…`,
  resolves to the owner admin user, attaches `req.admin` so existing
  permission decorators (events.create etc.) still work. Token-level
  scope check (read/write/admin) layers on top as defence in depth —
  a leaked read-only token cannot mutate even if its owner is super_admin.
- adminApiTokens route exposes list/create/revoke for admins (cookie-
  authed). Plaintext token is returned exactly once on creation.
- v1 surface mounted at /api/v1: POST/GET /events, GET /events/:id,
  POST /events/:id/photos (multipart, single file), GET
  /events/:id/share-link. Each endpoint annotated with @openapi JSDoc.

Documentation
- swagger-jsdoc + swagger-ui-express produce a live spec at
  /api/openapi.json and a Swagger UI at /api/docs (admin-gated).
- backend/scripts/generate-openapi.js writes docs/openapi.{json,yaml}
  to the repo so the spec is versioned.
- scripts/sync-api-docs.sh runs in pre-push: regenerates the spec and
  copies it into the picpeak-docs Nextra site at app/api/. Writes only,
  never commits or pushes the docs repo (PUSH_SKIP_DOCS=1 to bypass).

Frontend
- New Settings → API Tokens tab: generate, list, revoke. Plaintext
  tokens are shown once with a copy-to-clipboard control.

backend/server.js

@@ -532,6 +532,26 @@ app.use('/api/admin/css-templates', require('./src/routes/adminCssTemplates'));
 app.use('/api/admin/events', require('./src/routes/adminEventRename'));
 app.use('/api/admin/users', require('./src/routes/adminUsers'));
 app.use('/api/admin/event-types', require('./src/routes/adminEventTypes'));
+app.use('/api/admin/api-tokens', require('./src/routes/adminApiTokens'));
+// Public v1 API for n8n / external integrations (#322). Mounted under
+// /api/v1; auth handled per-route via apiTokenAuth (Bearer tokens).
+app.use('/api/v1', require('./src/routes/v1/events'));
+
+// Swagger UI for the v1 API. Admin-gated since it lists endpoint shapes
+// that should not be enumerable to anonymous users (a common reduce-info-leak hardening).
+{
+  const swaggerUi = require('swagger-ui-express');
+  const { adminAuth } = require('./src/middleware/auth');
+  const { getOpenApiSpec } = require('./src/openapi/spec');
+  app.get('/api/openapi.json', adminAuth, (_req, res) => res.json(getOpenApiSpec()));
+  app.use(
+    '/api/docs',
+    adminAuth,
+    swaggerUi.serve,
+    swaggerUi.setup(getOpenApiSpec(), { customSiteTitle: 'PicPeak API · v1' })
+  );
+}
+
 app.use('/api/invite', require('./src/routes/acceptInvite'));
 app.use('/api/public/settings', require('./src/routes/publicSettings'));
 app.use('/api/public', require('./src/routes/publicCMS'));