feat(voices): canonical voice corpus + dots.tts-optimized refs

Engine-agnostic voice corpus: canonical source clip + transcript per voice,
per-engine reference sets derived by derive.py from engines.yaml profiles.
First residents donut/glados/emmie/miranda optimized + verified clean for
dots.tts (sentence-bounded ref + accurate transcript — dots leaks reference
audio into output otherwise). canonical/ + transcripts/ tracked; derived/
gitignored (regenerable). Records the dots.tts burn-in in persistent-memory.

voices/transcripts/donut.txt

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+This is just not acceptable, Carl. I like my butterfly charm. It makes it so fairies like me, and it is pretty. It's part of my fit. I don't want to take it off. I don't see why I can't just wear two charms at the same time. Stupid angel of the caucus spaniel had like four or five tags.

voices/transcripts/emmie.txt

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+I think I mentioned but I read your book because my my dear friend Nupa told me that I should and every now and again I would see you come up. I don't know. I take my job seriously I guess and so interviews to me felt a lot like chess and it required so much energy.

voices/transcripts/glados.txt

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+Welcome to test chamber 4. You're doing quite well. Once again, excellent work. As part of a required test protocol, we will not monitor the next test chamber. You will be entirely on your own. Good luck! As part of a required test protocol, our previous statement suggesting that we would not monitor this chamber was an outright fabrication. Good job! As part of a required test protocol, we will not monitor the next test protocol.

voices/transcripts/miranda.txt

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+It's great. I mean, it's definitely comforting to go back to Australia when I come from there. So, you know, I get to see my parents, I get to see my friends and hang out. And I know the city really well because this was my fourth movie that I did in...