Upgrade Whisper to distil-large-v3, fix caller identity confusion, sort clips list

- Whisper base → distil-large-v3 for much better live transcription accuracy
- Add context hints to transcription (caller name, screening status)
- Increase beam_size 3→5 for better decoding
- Add explicit role clarification in caller system prompt so LLM knows Luke is the host
- Prefix host messages with [Host Luke] in LLM conversation
- Fix upload_clips episode list sorting (natural numeric order)
- Episodes 26-28 transcripts, data updates, misc fixes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/css/style.css

@@ -728,6 +728,10 @@ section h2 {
     color: var(--accent-hover);
 }
 
+.caller-btn.returning.active {
+    color: #fff;
+}
+
 /* Screening Badges */
 .screening-badge { font-size: 0.7rem; padding: 0.1rem 0.4rem; border-radius: var(--radius-sm); font-weight: bold; }
 .screening-badge.screening { background: var(--accent); color: white; animation: pulse 1.5s infinite; }