chore(services): rename services/provisioning -> services/platform-api

O.0 prep from OPERATOR-PLAN.md. Mechanical refactor before adding partner
management and operator-specific endpoints. The service now owns more than
just provisioning orchestration (it'll soon own partners, tenant lifecycle
actions, multi-audience JWT validation), so the name 'platform-api' reflects
its scope better.

What changed:
- Directory: services/provisioning/ -> services/platform-api/
- Package: @dezky/provisioning -> @dezky/platform-api
- Docker: container_name dezky-provisioning -> dezky-platform-api;
  compose service key 'provisioning' -> 'platform-api'; volume
  provisioning_node_modules -> platform_api_node_modules
- Portal: PROVISIONING_INTERNAL_URL env var -> PLATFORM_API_INTERNAL_URL,
  default URL http://provisioning:3001 -> http://platform-api:3001 in all
  three proxy routes (me.get.ts, tenants/index.post.ts, tenants/[slug]/
  reconcile.post.ts), plus NUXT_API_BASE updated
- Health endpoint service identifier and main.ts log lines updated to
  'dezky-platform-api'
- Docs swept: README, CLAUDE.md, SERVICES.md, AUTHENTIK-SETUP.md,
  NEXT-STEPS.md, TROUBLESHOOTING.md, OPERATOR-PLAN.md, traefik/dynamic.yml

What deliberately stays:
- Internal module names ProvisioningService / ProvisioningModule (those
  describe an orchestration sub-concern, not the service's purpose)
- Tenant.provisioningStatus / provisioningErrors field names (state
  per integration, not service name)
- File services/platform-api/src/tenants/provisioning.service.ts
- 'Hetzner provisioning' references in production-prep docs (infrastructure
  provisioning, unrelated)

Verified end-to-end after rename: /api/me returns 200 with profile + 2
tenants + subscription, /api/tenants/dezky/reconcile returns 200 with
Authentik integration still ok.

OPERATOR-PLAN.md O.0 checkboxes ticked.

apps/portal/server/api/tenants/index.post.ts

@@ -1,7 +1,7 @@
-// Dev/scaffolding: proxies POST /tenants to the provisioning service with the
-// logged-in user's access token. Lets you create a tenant from the browser
-// without minting tokens by hand. Will be replaced by a real "create workspace"
-// flow with proper UI later.
+// Dev/scaffolding: proxies POST /tenants to platform-api with the logged-in
+// user's access token. Lets you create a tenant from the browser without
+// minting tokens by hand. Will be replaced by a real "create workspace" flow
+// with proper UI later.
 
 import { getUserSession } from 'nuxt-oidc-auth/runtime/server/utils/session.js'
 
@@ -13,7 +13,7 @@ export default defineEventHandler(async (event) => {
   }
 
   const body = await readBody(event)
-  const base = process.env.PROVISIONING_INTERNAL_URL ?? 'http://provisioning:3001'
+  const base = process.env.PLATFORM_API_INTERNAL_URL ?? 'http://platform-api:3001'
 
   return $fetch(`${base}/tenants`, {
     method: 'POST',