multi-stage Dockerfile + player recap styles

Dockerfile: split into whisperx-base and runtime stages so app-only
changes skip the 10min pip install on rebuild. Example compose updated.

Player recap: replace hardcoded 'story so far' prompt with selectable
styles (story/diary/bullets/custom) via dropdown in Setup and Settings.

Settings: add NAT20_ONBOARDING_COMPLETED env var; fix merge logic so
env vars properly override defaults (not just empty DB values).

frontend/src/pages/Settings.tsx

@@ -62,6 +62,19 @@ export default function Settings() {
         <input className="input w-full" value={settings.world_context_path} onChange={(e) => set("world_context_path", e.target.value)} placeholder="...or path to a file inside the container" />
       </div>
 
+      <div className="card p-6 space-y-3 mb-6">
+        <h2 className="eyebrow">Player recap style</h2>
+        <select className="input w-full" value={settings.player_recap_style} onChange={(e) => set("player_recap_style", e.target.value)}>
+          <option value="story">Story Recap (previously on…)</option>
+          <option value="diary">Dear Diary</option>
+          <option value="bullets">Bullet Points</option>
+          <option value="custom">Custom Prompt</option>
+        </select>
+        {settings.player_recap_style === "custom" && (
+          <textarea className="input w-full h-32" value={settings.player_recap_custom_prompt} onChange={(e) => set("player_recap_custom_prompt", e.target.value)} placeholder="Write your own final-combine prompt. Use {'{summaries}'} where the chunk summaries should be inserted." />
+        )}
+      </div>
+
       <button className="btn-primary" onClick={save}>{saved ? "Saved" : "Save settings"}</button>
     </div>
   );