feat(deploy): consolidated dev stack with auto-provisioned Zitadel

Single docker-compose stack for local development (Postgres, Zitadel,
RabbitMQ, SeaweedFS + bucket init, Jaeger) plus an optional overlay to run
the .NET apps in Docker. up.ps1 orchestrates the full bootstrap: stack up,
stream-ticket keys, EF Core migrations and Zitadel provisioning.

- Zitadel is provisioned automatically (service-account PAT -> project +
  OIDC app with JWT access token); the generated ClientId is wired into
  Musify.Api user-secrets and .env. No manual console steps.
- ZITADEL_EXTERNAL_DOMAIN=host.docker.internal so token validation works
  both with local apps and full-docker.
- App Dockerfiles copy AppSettings*.json to lowercase so config loads on
  case-sensitive Linux; Worker image ships ffmpeg.
- Scripts split by responsibility (common/stream-keys/migrate/provision);
  apps overlay de-duped via YAML anchors.
- Remove the superseded standalone seaweedfs compose; point docs/development
  at the unified stack.

deploy/scripts/migrate.ps1

@@ -0,0 +1,15 @@
+#requires -Version 5.1
+# Applies EF Core migrations to the Musify database.
+[CmdletBinding()]
+param([Parameter(Mandatory)][string]$ConnectionString)
+
+$ErrorActionPreference = "Stop"
+$infraProject = Resolve-Path (Join-Path $PSScriptRoot "..\..\backend\Musify.Infrastructure")
+
+# The design-time factory reads the connection string from user-secrets.
+dotnet user-secrets set "Database:ConnectionString" $ConnectionString --project $infraProject | Out-Null
+
+# Infrastructure is also the startup project: it owns the IDesignTimeDbContextFactory
+# and the EFCore.Design package (Musify.Api does not reference Design).
+dotnet ef database update --project $infraProject --startup-project $infraProject --context Database
+if ($LASTEXITCODE -ne 0) { throw "EF Core migration failed" }