fix: use Keyword.get for API key to respect explicit nil, add ecto.migrate to test alias

- DeepSeek.complete: use Keyword.get/3 instead of || so passing api_key: nil
  is respected even when DEEPSEEK_API_KEY env var is set (nil is explicit
  'no key', not 'use default'). Also fixed base_url and model for consistency.
- test alias: add ecto.migrate after ecto.load so Oban migrations are applied,
  fixing 'Found version 12, but version 14 is required' on oban 2.23

lib/towerops/llm/deepseek.ex

@@ -19,9 +19,9 @@ defmodule Towerops.LLM.DeepSeek do
   @impl true
   def complete(messages, opts \\ []) do
     cfg = Application.get_env(:towerops, __MODULE__, [])
-    api_key = opts[:api_key] || cfg[:api_key]
-    base_url = present(opts[:base_url]) || present(cfg[:base_url]) || @default_base_url
-    model = present(opts[:model]) || present(cfg[:model]) || @default_model
+    api_key = Keyword.get(opts, :api_key, cfg[:api_key])
+    base_url = present(Keyword.get(opts, :base_url, nil)) || present(cfg[:base_url]) || @default_base_url
+    model = present(Keyword.get(opts, :model, nil)) || present(cfg[:model]) || @default_model
 
     if blank?(api_key) do
       {:error, :missing_api_key}

mix.exs

@@ -183,7 +183,7 @@ defmodule Towerops.MixProject do
       setup: ["deps.get", "ecto.setup", "assets.setup", "assets.build"],
       "ecto.setup": ["ecto.create", "ecto.migrate", "run priv/repo/seeds.exs"],
       "ecto.reset": ["ecto.drop", "ecto.setup"],
-      test: ["ecto.create --quiet", "ecto.load --quiet --skip-if-loaded", "test"],
+      test: ["ecto.create --quiet", "ecto.load --quiet --skip-if-loaded", "ecto.migrate --quiet", "test"],
       "assets.setup": ["tailwind.install --if-missing", "esbuild.install --if-missing"],
       "assets.build": ["compile", "tailwind towerops", "esbuild towerops"],
       "assets.deploy": [