radio: attach caller names to Q&A pairs from transcript intros

QAPair gets caller_name and caller_role fields populated by a new
attach_caller_names(pairs, transcript_segments) helper. For each pair,
finds the active opening intro at the question_start time (8s forward
tolerance, no backward limit — a caller's call can run for 10+ minutes
and the intro happens once at the start) and attaches the speaker name.

Validation on 9-episode test set:
  19/19 Q&A pairs (100%) now have caller names attached.

Examples of corrections from oracle attribution:
  2018-s10e18 @ 73:36  Christopher (was misattributed to "Tara")
  2015-s7e19 @ 35:45   William     (was misattributed to "Tara")
  2010-05-08-hr1       Jackie x3, Bruce
  2012-03-10-hr1       Adam x2
  2016-s8e43           John, Doug
  2017-s9e30           Tom, Denise x3, Charlie

speaker_oracle.py: adds speaker_at(time, intros) helper used both by the
existing resolve_speakers() and the new caller-name attachment. Also
adds the "let's fit/bring/put X in/on" intro pattern variant (caught
Charlie at 70:21 in 2017-s9e30 that "talk to X" missed).

download_full_archive.py: SSH keepalive every 30s + per-file retry-on-
failure (up to 3 attempts with reconnect). Earlier run hung on a dead
connection at file 109 of 589 with no recovery; restarted run is now
running at ~10 MB/s vs ~2-3 MB/s before.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

projects/radio-show/audio-processor/benchmark.py

@@ -17,7 +17,7 @@ ensure_cuda_libs()
 import torch
 from src.config import load_config
 from src.diarizer import diarize, VoiceProfileStore
-from src.qa_extractor import load_diarized_transcript, extract_qa_pairs
+from src.qa_extractor import load_diarized_transcript, extract_qa_pairs, attach_caller_names
 from rich.console import Console
 from rich.table import Table
 
@@ -180,8 +180,16 @@ for ep, transcript_path, audio_dur, _ in trans_results:
     diarization_path = trans_ep_dir / "diarization.json"
     segments = load_diarized_transcript(transcript_path, diarization_path)
     pairs    = extract_qa_pairs(segments)
+
+    # Attach caller names from transcript intros
+    with open(transcript_path) as f:
+        td = _json.load(f)
+    attach_caller_names(pairs, td.get("segments", []))
+
+    named = sum(1 for p in pairs if p.caller_name)
+    name_str = ", ".join(p.caller_name for p in pairs if p.caller_name) or "—"
     qa_rows.append((ep.stem, len(pairs)))
-    console.print(f"  {ep.stem}: {len(pairs)} Q&A pairs")
+    console.print(f"  {ep.stem}: {len(pairs)} pairs ({named} named: {name_str})")
 
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