feat: add Queue-based async server provisioning

- Add Cloudflare Queue for async server provisioning workflow
- Implement VPS provider abstraction (Linode, Vultr)
- Add provisioning API endpoints with API key authentication
- Fix race condition in balance deduction (atomic query)
- Remove root_password from Queue for security (fetch from DB)
- Add IP assignment wait logic after server creation
- Add rollback/refund on all failure cases

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

wrangler.toml

@@ -8,12 +8,18 @@ workers_dev = true
 [ai]
 binding = "AI"
 
-# D1 Database binding (cloud-instances-db: 1,119 servers)
+# D1 Database binding (cloud-instances-db: server specs, pricing)
 [[d1_databases]]
 binding = "DB"
 database_name = "cloud-instances-db"
 database_id = "bbcb472d-b25e-4e48-b6ea-112f9fffb4a8"
 
+# D1 Database binding (telegram-conversations: users, deposits, orders)
+[[d1_databases]]
+binding = "USER_DB"
+database_name = "telegram-conversations"
+database_id = "c285bb5b-888b-405d-b36f-475ae5aed20e"
+
 # KV Cache binding for rate limiting and response caching
 [[kv_namespaces]]
 binding = "CACHE"
@@ -22,3 +28,14 @@ id = "c68cdb477022424cbe4594f491390c8a"
 # Observability
 [observability]
 enabled = true
+
+# Queue for async server provisioning
+[[queues.producers]]
+queue = "provision-queue"
+binding = "PROVISION_QUEUE"
+
+[[queues.consumers]]
+queue = "provision-queue"
+max_batch_size = 1
+max_retries = 3
+dead_letter_queue = "provision-queue-dlq"