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/Sync Bookmarks.yml

@@ -3,20 +3,8 @@ docs: "## Sync KOReader Bookmarks\n\nSynchronizes bookmarks separately from prog
   \ bookmark\" menu\n- Shown in \"Bookmarks\" panel\n- Quick access via \"Go to bookmark\"\n- Exportable to JSON\n- Can be edited/deleted\n\n**Use Cases:**\n- Quick navigation aids\n- Chapter markers\n- Important passages\n- Reading progress points\n- Study session markers"
 http:
   body:
-    json:
-      books:
-      - bookmarks:
-        - chapter: 3
-          datetime: '2026-01-30T19:55:00Z'
-          notes: Marked this chapter as important
-          page: 45
-          pos0: epubcfi(/6/4/2:15)
-          pos1: epubcfi(/6/4/2:20)
-          text: Important passage
-          type: bookmark
-        uuid: '{{media_item_id}}'
-      library_id: optional-library-uuid
     type: json
+    data: "{\n  \"book_uuid\": \"{{media_item_id}}\",\n  \"bookmarks\": [\n    {\n      \"chapter\": 3,\n      \"datetime\": \"2026-01-30T19:55:00Z\",\n      \"page\": 45,\n      \"pos0\": \"epubcfi(/6/4/2:15)\",\n      \"pos1\": \"epubcfi(/6/4/2:20)\",\n      \"text\": \"Important passage\",\n      \"type\": \"bookmark\"\n    }\n  ]\n}"
   headers:
   - key: Content-Type
     value: application/json