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>

database/migrations/1770000002100_ranges_capture.ts

@@ -0,0 +1,12 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+/** Ranges whose XOVER chunks are kept in the corpus (CORPUS_DIR) for the grouping sweeps. */
+export default class extends BaseSchema {
+  async up() {
+    this.schema.raw(`ALTER TABLE ranges ADD COLUMN IF NOT EXISTS capture boolean NOT NULL DEFAULT false`)
+  }
+
+  async down() {
+    this.schema.raw(`ALTER TABLE ranges DROP COLUMN IF EXISTS capture`)
+  }
+}