feat(infra): add PostgreSQL provider switch (soft migration, default SqlServer) + local postgres:17 service

src/GreenHome.Api/appsettings.Development.json

@@ -5,8 +5,12 @@
       "Microsoft.AspNetCore": "Warning"
     }
   },
+  "Database": {
+    "Provider": "SqlServer"
+  },
   "ConnectionStrings": {
-    "Default": "Server=.;Integrated Security=False;Trusted_Connection=True;Encrypt=false;MultipleActiveResultSets=true;Database=GreenHomeDb;"
+    "Default": "Server=.;Integrated Security=False;Trusted_Connection=True;Encrypt=false;MultipleActiveResultSets=true;Database=GreenHomeDb;",
+    "Postgres": "Host=localhost;Port=5432;Database=greenhome;Username=greenhome;Password=greenhome"
   },
   "AvanakVoiceCall": {
     "Token": "A948B776B90CFD919B0EC60929714136CCB49DDB"

src/GreenHome.Api/docker-compose.yaml

@@ -33,7 +33,24 @@ services:
     networks:
       - greenNetwork
 
+  postgres:
+    image: postgres:17-alpine
+    restart: unless-stopped
+    environment:
+      POSTGRES_DB: greenhome
+      POSTGRES_USER: greenhome
+      POSTGRES_PASSWORD: greenhome
+    ports:
+      - "5432:5432"
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    networks:
+      - greenNetwork
+
 networks:
   serviceNetwork:
     name: greenNetwork
     external: true
+
+volumes:
+  pgdata:

src/GreenHome.Infrastructure/DependencyInjection.cs

@@ -13,6 +13,7 @@ using GreenHome.Infrastructure.Services.Telemetry;
 using GreenHome.Infrastructure.Services.Usage;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
+using Npgsql.EntityFrameworkCore.PostgreSQL;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace GreenHome.Infrastructure;
@@ -28,9 +29,19 @@ public static class DependencyInjection
         IConfiguration configuration)
     {
         // Entity Framework
+        // Provider is switchable via config ("Database:Provider" = "SqlServer" | "Postgres")
+        // to allow a soft migration: default stays SqlServer until cutover.
+        var provider = configuration["Database:Provider"] ?? "SqlServer";
         services.AddDbContext<GreenHomeDbContext>(options =>
+        {
+            if (provider == "Postgres")
+            {
+                options.UseNpgsql(configuration.GetConnectionString("Postgres"));
+            }
+            else
             {
                 options.UseSqlServer(configuration.GetConnectionString("Default"));
+            }
         });
 
         // Auth

src/GreenHome.Infrastructure/GreenHome.Infrastructure.csproj

@@ -14,6 +14,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.9" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="9.0.9" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="9.0.4" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.9">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>