docs(rust): protocol 14 — Backpacks, as built; D340, D341 (PROTOCOL §20.4, PLAN_REDESIGNS §11.3.4)

- PROTOCOL §20.4: hello's integrations.backpacks.sizes, backpacks.read and its
  reply (display, blueprint, overflow, pageSize), the refusals, the sidecar
  forward, and the site's routes and Bigger backpack step.
- PLAN_REDESIGNS: D340 (a slot shows the game's name, no icons; R9 stands) and
  D341 (a blueprint names what it makes), answered before any code; §11.3.4
  lists the points settled in code so they can be overruled; §11.3.3 notes the
  walk needs real Steam ids.
- android PLAN: the account screen's Backpack section.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

android/PLAN.md

@@ -1455,7 +1455,7 @@ push, and Play (M6–M8) follow the designed app.
 
     | Screen | Route | Reads |
     | --- | --- | --- |
-    | **My Rust account** | `player/rust` | `GET /player/rust/links`, `POST /player/rust/link`, `DELETE …/links/{steamId}`, `GET /player/rust/permissions`, `GET /player/rust/economics` (the Coins section, 2026-10-12, [`PLAN_REDESIGNS.md`](../modules/rust/PLAN_REDESIGNS.md) §11.2: one card per server, "last known" when a server did not answer, the reason where it has no Economics, and left out on a 404 from an older module) |
+    | **My Rust account** | `player/rust` | `GET /player/rust/links`, `POST /player/rust/link`, `DELETE …/links/{steamId}`, `GET /player/rust/permissions`, `GET /player/rust/economics` (the Coins section, 2026-10-12, [`PLAN_REDESIGNS.md`](../modules/rust/PLAN_REDESIGNS.md) §11.2: one card per server, "last known" when a server did not answer, the reason where it has no Economics, and left out on a 404 from an older module), `GET /player/rust/servers` + `GET /player/rust/backpacks` (the Backpack section, 2026-10-12, §11.3: one card per server, an Open button per linked account that reads once per press, the slots as pages of four-wide rows named by the game, D340, overflow marked; "not installed" on a 409, and left out with Coins on that 404) |
 
     #### The gate is `rust`, and `PLAYER` means staff too