fix(bruno): convert drifted body keys to body.data — CLI scenario runs now carry bodies

Follow-up to the sweep route audit, correcting its diagnosis: the CLI
DOES read .yml bodies — via OpenCollection's `body.data` string form
(the NewDevDBSetup script always worked because it used it). The
failing scenario POSTs used `body.json` (structured) / `body.jsonBody`
(string) — keys the CLI silently ignores, sending Content-Length: 0
with form-urlencoded content-type, so every server bind failed.

- 81 bodies converted to data-form (json maps serialized; jsonBody
  strings kept verbatim, {{vars}} intact).
- 6 pre-existing TRUNCATED payloads repaired: the original generator
  cut bodies at the first {{var}} (every SHA-256-identified scenario
  plus Sync Progress/Sync Bookmarks shipped mid-JSON and 400'd from
  day one). Rewritten whole, faithful to each file's documented
  purpose; book_sha256/book_uuid added to the environment.
- environments: opds_base_url correction from the sweep retained.

Verified live against the rebuilt dev container: the full koreader
scenario tree runs green through `bru run` — 14/14 (202s across
immediate/checkpoint/SHA-256 progress, 200s bookmarks, highlights,
notes; SHA-256 book identification exercised against a real
file_sha256).

bruno/devices/koreader/scenarios/Immediate Sync - Page Turn.yml

@@ -3,14 +3,8 @@ docs: "## Immediate Sync - Page Turn\n\nReal-time progress sync triggered immedi
   - Research and study\n- Testing sync functionality\n- When power source available\n\n**When NOT to Use:**\n- Battery conservation needed\n- Unstable network\n- Extended reading sessions\n- Background sync preferred"
 http:
   body:
-    json:
-      books:
-      - chapter: 3
-        percentage: 0.45678
-        timestamp: '2026-01-30T20:00:00Z'
-        uuid: '{{media_item_id}}'
-      sync_mode: immediate
     type: json
+    data: "{\n  \"books\": [\n    {\n      \"chapter\": 3,\n      \"percentage\": 0.45678,\n      \"timestamp\": \"2026-01-30T20:00:00Z\",\n      \"uuid\": \"{{media_item_id}}\"\n    }\n  ],\n  \"sync_mode\": \"immediate\"\n}"
   headers:
   - key: Content-Type
     value: application/json