Corpus: stored XOVER chunks for the grouping sweeps

Ranges marked `capture` keep their XOVER chunks in CORPUS_DIR
(corpus/<group>/<start>-<end>/, edge-bench's layout, range.json once
complete; only chunks that inflate). The prefetcher reads a stored chunk
instead of fetching it, so a reset re-indexes them without the news
server; a chunk a worker reports corrupt goes from the corpus too.

edge-bench gets --releases (release chunks without payload, with their
first subjects) and ships in the edge image; deploy/corpus_sweep.py marks
more ranges (capture), replays the corpus with the deployed build (replay)
and reports suspects and the change since the previous build (report).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -32,10 +32,12 @@ WORKDIR /src
 COPY edge ./
 RUN --mount=type=cache,target=/usr/local/cargo/registry \
     --mount=type=cache,target=/src/target \
-    cargo build --release --locked --bin edge-node \
- && cp target/release/edge-node /usr/local/bin/edge-node
+    cargo build --release --locked --bin edge-node --bin edge-bench \
+ && cp target/release/edge-node target/release/edge-bench /usr/local/bin/
 
 FROM debian:bookworm-slim AS edge
 COPY --from=edge-build /usr/local/bin/edge-node /usr/local/bin/edge-node
+# edge-bench replays the corpus for the grouping sweeps (deploy/corpus_sweep.py).
+COPY --from=edge-build /usr/local/bin/edge-bench /usr/local/bin/edge-bench
 USER 1000:1000
 ENTRYPOINT ["/usr/local/bin/edge-node"]