Add booking stack, client deploys, and back-office updates

- deploy/booking: shared Easy!Appointments stack with brand-matched
  wizard (flatpickr recolor, single-tenant provider hide, iframe
  auto-fit height reporter)
- deploy/clients: per-client isolated nginx compose stacks with
  _template scaffold, new-client.sh, and happynails live site
- deploy/backup: smb-db backup script
- n8n: booking-sync workflow; onboarding tweaks
- playbooks: lead-to-customer lifecycle + outreach
- templates: nail-studio landing previews
- backoffice: app/db/init/compose updates

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy/clients/README.md

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+# clients/ — one isolated stack per business client
+
+Each signed client gets their **own Compose project** (`smb-client-<slug>`) running a
+single lightweight `nginx:alpine` container that serves *their* static site on *their*
+domain. Clients are fully separated: independent lifecycle, logs, and removal; no shared
+container or state. Booking and lead data still flow into the **shared CRM** (Postgres
+source of truth) via the n8n webhooks baked into each client's page.
+
+## Why a container per client (not one shared host)
+- **Isolation** — update / restart / remove one client without touching any other.
+- **Clean billing & offboarding** — `docker compose down` removes exactly that client.
+- **Cheap** — static nginx idles at a few MB; capped at 64 MB each, so dozens fit the 16 GB box.
+
+## Layout
+```
+deploy/clients/
+├── _template/            # DON'T deploy — the source template
+│   ├── docker-compose.yml   (name: smb-client-${CLIENT_SLUG})
+│   ├── .env.example
+│   └── site/index.html
+├── new-client.sh         # scaffolds a client folder from _template/
+└── <slug>/               # one folder per real client (created by the script)
+    ├── docker-compose.yml
+    ├── .env              (CLIENT_SLUG, CLIENT_DOMAIN)
+    └── site/             (the client's branded page)
+```
+
+## Add a client
+```bash
+cd deploy/clients
+./new-client.sh happynails happynails.de ../../templates/landing/preview-happynails
+```
+Then follow the printed steps: add the Caddy block + reload, point DNS, and `docker compose up -d`
+on the homelab. Each client lives at `/home/mivanchenko/clients/<slug>/` on the box.
+
+## How this fits the whole system (compose groups)
+```
+edge/        caddy                    → TLS, routing, basic-auth   (one, shared)
+automation/  n8n (+ postgres, redis)  → n8n.mivanchenko.de         (one, shared)
+crm/         smb-db + smb-crm         → onboard.mivanchenko.de/crm (one, shared)
+demos/       smb-demos                → demos.mivanchenko.de       (prospect previews)
+clients/     smb-client-<slug> × N    → each client's domain       (one per client) ← this dir
+```
+Shared infra (edge / automation / crm) stays single; only the client-facing sites multiply,
+one isolated stack each. Previews for *prospects* stay in `demos/` until they sign — then
+scaffold them a real isolated stack here.