feat: implement Call Center queues (mod_callcenter)

- Investigated the real callcenter_config command surface via
  'help callcenter_config' on the running FreeSWITCH before writing any
  code: queues only have load/unload/reload (static XML + reload, no
  'queue add' exists), while agents and tiers are fully dynamic via ESL
  commands (agent add, tier add) -- no file involved. This shapes the next
  phase (Agents/Tiers) differently from this one.
- queues table (tenant-scoped, RLS): strategy, moh/announce, wait times,
  tier rules, discard/abandoned handling, skip-agents-with-external-calls,
  recording_enabled
- packages/telephony: buildQueueXml()
- infrastructure/freeswitch: our own callcenter.conf.xml override (empties
  the vanilla static agents/tiers -- those become fully dynamic in the next
  phase) that includes callcenter_queues.conf.d/*.xml via X-PRE-PROCESS,
  same pattern as the Sofia gateway directory
- apps/api/src/queues: CRUD (POST/GET/GET:id/DELETE) using the queues.view/
  .manage permissions already in the seed
- b2bcall-fs-config (queue-sync.ts): one XML file per queue on a shared
  volume, synced via Redis pub/sub (b2bcall:queues:sync) on create/delete
  and once at boot -- same shape as trunk-sync.ts
- confirmed manually against the real FreeSWITCH, before coding the sync
  logic: 'queue load <name>' fails ('Invalid Queue not found!') for a file
  added after boot -- needs 'reloadxml' first to repopulate the in-memory
  XML tree from disk; after that, 'queue reload <name>' alone handles both
  create and update, no need to distinguish load vs reload
- verified end-to-end: created a queue (ROUND_ROBIN, maxWaitTime=120,
  discardAbandonedAfter=90), 'callcenter_config queue list' showed the
  correct values on the FreeSWITCH side; deleted it, list went back empty

docs/QUEUES.md

packages/database/prisma/schema.prisma

@@ -38,6 +38,7 @@ model Tenant {
   trunks           Trunk[]
   dialplanExtensions DialplanExtension[]
   dialplanVersions   DialplanVersion[]
+  queues             Queue[]
 
   @@map("tenants")
 }
@@ -379,3 +380,61 @@ model DialplanVersion {
   @@index([tenantId, context, status])
   @@map("dialplan_versions")
 }
+
+enum QueueStrategy {
+  LONGEST_IDLE_AGENT
+  ROUND_ROBIN
+  TOP_DOWN
+  AGENT_WITH_LEAST_TALK_TIME
+  AGENT_WITH_FEWEST_CALLS
+  SEQUENTIALLY_BY_AGENT_ORDER
+  RING_ALL
+  RING_PROGRESSIVELY
+
+  @@map("queue_strategy")
+}
+
+// Tabela tenant-scoped protegida por RLS (agente.md secao 50-51). O nome no
+// FreeSWITCH é `<queue.id>@<tenant.telephonyDomain>` — mod_callcenter usa
+// um namespace unico compartilhado entre tenants (nao ha equivalente ao
+// diretorio por-arquivo do Sofia pra isolar por tenant, ver docs/QUEUES.md).
+model Queue {
+  id                     String        @id @default(uuid()) @db.Uuid
+  tenantId               String        @map("tenant_id") @db.Uuid
+
+  name                   String
+  description            String?
+
+  strategy               QueueStrategy @default(LONGEST_IDLE_AGENT)
+
+  mohSound               String?       @map("moh_sound")
+  announceSound          String?       @map("announce_sound")
+  announceFrequency      Int           @default(0) @map("announce_frequency")
+
+  maxWaitTime            Int           @default(0) @map("max_wait_time")
+  maxWaitTimeWithNoAgent Int           @default(0) @map("max_wait_time_with_no_agent")
+
+  agentNoAnswerStatus    String?       @map("agent_no_answer_status")
+
+  tierRulesApply         Boolean       @default(false) @map("tier_rules_apply")
+  tierRuleWaitSecond     Int           @default(300) @map("tier_rule_wait_second")
+
+  discardAbandonedAfter  Int           @default(60) @map("discard_abandoned_after")
+  abandonedResumeAllowed Boolean       @default(false) @map("abandoned_resume_allowed")
+
+  skipAgentsWithExternalCalls Boolean  @default(true) @map("skip_agents_with_external_calls")
+
+  recordingEnabled       Boolean       @default(false) @map("recording_enabled")
+
+  enabled                Boolean       @default(true)
+
+  createdAt              DateTime      @default(now()) @map("created_at")
+  updatedAt              DateTime      @updatedAt @map("updated_at")
+  deletedAt              DateTime?     @map("deleted_at")
+
+  tenant                 Tenant        @relation(fields: [tenantId], references: [id])
+
+  @@unique([tenantId, name])
+  @@index([tenantId])
+  @@map("queues")
+}