fix: punctuate raw transcript, strip JSON code fences, filter null speaker names

- llm: punctuate() adds punctuation/capitalisation without changing words
- llm: _strip_code_fences() handles markdown-wrapped JSON from gemma3
- llm: filter string 'null' from identify_speakers result
- pipeline: punctuate raw_text in parallel with refine for solo recordings

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

api/pipeline.py

@@ -74,15 +74,14 @@ async def _run_solo_pipeline(cfg, wav_path, output_dir, instructions):
     await broadcast({"event": "transcribed", "raw": raw_text})
 
     client = OllamaClient(base_url=cfg["ollama"]["base_url"])
-    refined = await client.refine(
-        raw_text=raw_text,
-        instructions=instructions,
-        model=cfg["ollama"]["model"],
+    punctuated, refined = await asyncio.gather(
+        client.punctuate(raw_text, model=cfg["ollama"]["model"]),
+        client.refine(raw_text=raw_text, instructions=instructions, model=cfg["ollama"]["model"]),
     )
+    title, tldr = await client.generate_title_and_tldr(refined, model=cfg["ollama"]["model"])
 
     dt = datetime.now()
-    title, tldr = await client.generate_title_and_tldr(refined, model=cfg["ollama"]["model"])
-    paths = write_solo_docs(raw_text=raw_text, refined=refined, output_dir=output_dir, dt=dt, title=title, tldr=tldr)
+    paths = write_solo_docs(raw_text=punctuated, refined=refined, output_dir=output_dir, dt=dt, title=title, tldr=tldr)
 
     await state.set_status(Status.IDLE)
     await broadcast({