feat(scheduling): dezky Scheduling — Calendly-style booking on Stalwart calendars

First-party booking system on top of Stalwart calendars (no third-party
scheduling dependency). Hosts expose public booking pages; visitors pick a
slot computed from the host's live Stalwart free/busy, and confirming writes
the event to the host's calendar and sends a dezky-branded confirmation with
an .ics.

platform-api (services/platform-api/src/scheduling):
- Schemas: Host, StalwartCredential (AES-256-GCM at rest), AvailabilitySchedule,
  EventType, Booking, SlotLock (unique (hostId,startUtc) + TTL).
- StalwartCalendarModule: JMAP gateway (free/busy via Principal/getAvailability,
  event create/delete, scheduleAgent=client) + on-behalf app-password
  provisioning. CredentialCipher for at-rest encryption.
- DST-correct slot engine (Luxon) with unit tests; two-layer double-booking
  guard (atomic SlotLock + live free/busy re-check).
- Booking confirm/cancel/reschedule, branded email + .ics via JMAP submission,
  self-service manage tokens. /api/v1 public + tenant-gated admin routes,
  per-IP rate limiting.

apps/booking: standalone public, whitelabel booking app (booking.dezky.eu) —
path-based tenant resolution, per-tenant brand colour, booking + manage flows.

apps/portal: admin scheduling page (hosts, event types, availability, bookings
with edit/delete + admin cancel/reschedule) and proxy routes.

infra: booking dev service in docker-compose; scheduling env vars.

apps/booking/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "@dezky/booking",
+  "version": "0.0.1",
+  "private": true,
+  "description": "dezky Scheduling — public booking app (booking.dezky.eu). Unauthenticated, whitelabel per tenant.",
+  "scripts": {
+    "dev": "TMPDIR=/tmp nuxt dev --host 0.0.0.0 --port 3000",
+    "build": "nuxt build",
+    "start": "node .output/server/index.mjs",
+    "generate": "nuxt generate",
+    "preview": "nuxt preview",
+    "typecheck": "nuxt typecheck"
+  },
+  "dependencies": {
+    "luxon": "^3.5.0",
+    "nuxt": "^4.4.7",
+    "vue": "^3.5.0",
+    "vue-router": "^4.4.0"
+  },
+  "devDependencies": {
+    "@types/luxon": "^3.4.2",
+    "@types/node": "^20.0.0",
+    "typescript": "^5.6.0",
+    "vue-tsc": "^3.2.6"
+  },
+  "packageManager": "pnpm@9.12.0"
+}