ticket: site metadata header + scannable Albanian ticket; widen barcode

- site_config gains optional park identity (park_name, operator_name, nius,
  address, phone, email); additive Drizzle migration 0001. GET/PUT
  /api/site-config read/write the full config (PUT partial patch, admin only);
  SiteSettings + SetupWizard expose the fields.
- renderTicket() prints an Albanian header sourced from site_config, the
  all-numeric 13-digit ticket id (12 random + Luhn) as Code128, large digits,
  and a lost-ticket footer. CP852 codepage so ë/ç render.
- Widen the Code128 module width 2->3 and height 80->100 dots so the
  short-range "Simple" QR/barcode reader decodes reliably (was barely reading
  at module width 2 on the 80mm head).

See wiki/concepts/site-metadata.md and ticket-encoding.md.

apps/server/.env.example

@@ -8,6 +8,13 @@
 # Generate one with:  openssl rand -hex 32
 JWT_SECRET=
 
+# Dedicated HMAC key for signing the append-only event ledger (>=16 chars).
+# Generate with:  openssl rand -hex 32
+# If unset, the server falls back to JWT_SECRET (logged as a warning) — fine for
+# dev, but set a dedicated key before production. Events store the key that signed
+# them (keyId), so verifyChain still validates a chain that spans a key change.
+EVENT_SIGNING_KEY=
+
 # Optional ----------------------------------------------------------------
 # PORT=3000
 # HOST=0.0.0.0                 # interface to bind. 127.0.0.1 = loopback only.