Clean up stale directories and fix monorepo structure

- Remove remaining home-assistant-integration/ and dev-config/
- Move dashboard to repo root for proper monorepo layout
- Remove crash dumps and symlinks
- Clean structure: server/ and dashboard/ at root level

dashboard/lib/dashboard/application.ex

@@ -0,0 +1,35 @@
+defmodule Dashboard.Application do
+  # See https://hexdocs.pm/elixir/Application.html
+  # for more information on OTP Applications
+  @moduledoc false
+
+  use Application
+
+  @impl true
+  def start(_type, _args) do
+    children = [
+      DashboardWeb.Telemetry,
+      {DNSCluster, query: Application.get_env(:dashboard, :dns_cluster_query) || :ignore},
+      {Phoenix.PubSub, name: Dashboard.PubSub},
+      # Start the Finch HTTP client for sending emails
+      {Finch, name: Dashboard.Finch},
+      # Start a worker by calling: Dashboard.Worker.start_link(arg)
+      # {Dashboard.Worker, arg},
+      # Start to serve requests, typically the last entry
+      DashboardWeb.Endpoint
+    ]
+
+    # See https://hexdocs.pm/elixir/Supervisor.html
+    # for other strategies and supported options
+    opts = [strategy: :one_for_one, name: Dashboard.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+
+  # Tell Phoenix to update the endpoint configuration
+  # whenever the application is updated.
+  @impl true
+  def config_change(changed, _new, removed) do
+    DashboardWeb.Endpoint.config_change(changed, removed)
+    :ok
+  end
+end

dashboard/lib/dashboard/mailer.ex

@@ -0,0 +1,3 @@
+defmodule Dashboard.Mailer do
+  use Swoosh.Mailer, otp_app: :dashboard
+end