scriberr: fit GPU 1 beside intern-decision — 120 s Parakeet slices + expandable_segments

Measured Parakeet peak on a 35-min file (n=3 each, deterministic): 300 s
9,384 MiB, 120 s 6,510, 60 s 5,976, 10 s 5,634 (fixed floor); with
expandable_segments 120 s 5,496 and 60 s 5,502. Verified 5,496 under the
recreated container's own env. Transcripts: 95.8% word-sequence similarity
vs 300 s, diffs mostly casing/punctuation.

stacks/scriberr/.env.example

@@ -42,3 +42,9 @@ SCRIBERR_SECURE_COOKIES=false
 # ⚠ That key also reaches PAID passthrough models (GLM, Kimi) on a shared
 #   tab — keep the configured model on a free local seat.
 # SCRIBERR_OPENAI_API_KEY=
+
+# GPU 1 memory budget (2026-09-30). Parakeet slice length in seconds and the
+# torch allocator mode; see compose.yaml for the measurements. Defaults apply
+# when unset; override only with a re-measured peak.
+# SCRIBERR_PARAKEET_CHUNK_SECS=120
+# SCRIBERR_PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True