feat(print): cloud↔local print-agent foundation (hub, pairing, registry)

First phase of auto-discovered printing for cloud-hosted cafés whose printers are
on the local network (the cloud can't reach a LAN/USB printer directly). Adds:
- PrintAgent + PrintDevice entities (+ additive migration) — a per-café local
  bridge and the printers it reports.
- PrintAgentHub (/hubs/print-agent): agents connect outbound, authenticated by a
  token in access_token (not the user JWT); ReportPrinters upserts devices,
  PrintJob is pushed to the agent, JobResult/Heartbeat come back.
- PrintAgentRegistry (singleton): tracks connected agents and dispatches a job to
  one, awaiting its ack with a timeout.
- Pairing: POST /cafes/{id}/print-agents/pairing-code (ManagePrintSettings) issues
  a short one-time code; anonymous POST /print-agent/claim redeems it for a
  long-lived token (only its SHA-256 hash is stored). List + revoke endpoints,
  online status from the registry.

Inert until Phase 2 routes jobs through it and the agent app (Phase 3) connects.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Meezi.Infrastructure/Data/Migrations/AppDbContextModelSnapshot.cs

@@ -1935,6 +1935,104 @@ namespace Meezi.Infrastructure.Data.Migrations
                     b.ToTable("PlatformSettings");
                 });
 
+            modelBuilder.Entity("Meezi.Core.Entities.PrintAgent", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text");
+
+                    b.Property<string>("BranchId")
+                        .HasColumnType("text");
+
+                    b.Property<string>("CafeId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<DateTime?>("DeletedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<DateTime?>("LastSeenAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(120)
+                        .HasColumnType("character varying(120)");
+
+                    b.Property<string>("PairingCode")
+                        .HasMaxLength(16)
+                        .HasColumnType("character varying(16)");
+
+                    b.Property<DateTime?>("PairingCodeExpiresAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<bool>("Revoked")
+                        .HasColumnType("boolean");
+
+                    b.Property<string>("TokenHash")
+                        .HasMaxLength(128)
+                        .HasColumnType("character varying(128)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("BranchId");
+
+                    b.HasIndex("CafeId");
+
+                    b.HasIndex("PairingCode");
+
+                    b.HasIndex("TokenHash");
+
+                    b.ToTable("PrintAgents");
+                });
+
+            modelBuilder.Entity("Meezi.Core.Entities.PrintDevice", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text");
+
+                    b.Property<string>("AgentId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<string>("CafeId")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<DateTime?>("DeletedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("DisplayName")
+                        .IsRequired()
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.Property<string>("Kind")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("character varying(20)");
+
+                    b.Property<DateTime>("LastSeenAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("SystemName")
+                        .IsRequired()
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AgentId", "SystemName")
+                        .IsUnique();
+
+                    b.ToTable("PrintDevices");
+                });
+
             modelBuilder.Entity("Meezi.Core.Entities.PushDevice", b =>
                 {
                     b.Property<string>("Id")
@@ -3150,6 +3248,35 @@ namespace Meezi.Infrastructure.Data.Migrations
                     b.Navigation("Order");
                 });
 
+            modelBuilder.Entity("Meezi.Core.Entities.PrintAgent", b =>
+                {
+                    b.HasOne("Meezi.Core.Entities.Branch", "Branch")
+                        .WithMany()
+                        .HasForeignKey("BranchId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("Meezi.Core.Entities.Cafe", "Cafe")
+                        .WithMany()
+                        .HasForeignKey("CafeId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Branch");
+
+                    b.Navigation("Cafe");
+                });
+
+            modelBuilder.Entity("Meezi.Core.Entities.PrintDevice", b =>
+                {
+                    b.HasOne("Meezi.Core.Entities.PrintAgent", "Agent")
+                        .WithMany("Devices")
+                        .HasForeignKey("AgentId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Agent");
+                });
+
             modelBuilder.Entity("Meezi.Core.Entities.QueueTicket", b =>
                 {
                     b.HasOne("Meezi.Core.Entities.Branch", "Branch")
@@ -3473,6 +3600,11 @@ namespace Meezi.Infrastructure.Data.Migrations
                     b.Navigation("Payments");
                 });
 
+            modelBuilder.Entity("Meezi.Core.Entities.PrintAgent", b =>
+                {
+                    b.Navigation("Devices");
+                });
+
             modelBuilder.Entity("Meezi.Core.Entities.Shift", b =>
                 {
                     b.Navigation("Transactions");