Rework caller buttons and info panel for slim backgrounds

Backend:
- /api/callers now returns slim fields: identity, situation, signature,
  secret_want, voice (was: energy_level, emotional_state,
  communication_style, signature_detail, situation_summary, pool_name,
  call_shape).
- /api/call/{caller_key} caller_info swapped to slim fields too.

Frontend:
- Caller buttons stripped to name + shortcut + returning star. No more
  energy-dots or shape-badges — those systems are being deleted.
- Caller info panel shows identity (title) / situation / signature
  (quoted detail) / secret_want (amber italic, host-only).
- Removed .energy-dot, .shape-badge, .info-badge.shape/energy/emotion
  CSS rules. Added .caller-identity and .caller-secret-want.

frontend/index.html

@@ -73,14 +73,13 @@
                 <div id="call-status" class="call-status">No active call</div>
                 <div id="caller-info-panel" class="caller-info-panel hidden">
                     <div class="caller-info-row">
-                        <span id="caller-shape-badge" class="info-badge shape"></span>
-                        <span id="caller-energy-badge" class="info-badge energy"></span>
-                        <span id="caller-emotion" class="info-badge emotion"></span>
                         <span id="caller-model-badge" class="info-badge model"></span>
                         <select id="caller-model-override" class="caller-model-override hidden"></select>
                     </div>
-                    <div id="caller-signature" class="caller-signature"></div>
+                    <div id="caller-identity" class="caller-identity"></div>
                     <div id="caller-situation" class="caller-situation"></div>
+                    <div id="caller-signature" class="caller-signature"></div>
+                    <div id="caller-secret-want" class="caller-secret-want"></div>
                     <details id="caller-background-details" class="caller-background-full">
                         <summary>Full Background</summary>
                         <div id="caller-background"></div>