docs(rust): protocol 14 — Economics, as built (PROTOCOL §20.3, PLAN_REDESIGNS §11.2.4)

PROTOCOL.md §20.3 specifies what §11.2.2 designed and the code now does:
integrations.economics, economics.pay / .balances / .adjust and their replies
and refusals, the tally's `balance` (a value; a nameless frame is an offline
player), economics.wiped with `newSave`, the three sidecar forwards, and the
website's half. §20's heading now covers the optional plugins too.

PLAN_REDESIGNS §11.2.4 records the build (compiled on both rigs, then given
back their protocol 13 bridge) and names the six points the design left open
that the code settled, so the org lead can overrule any of them. The app
plan's Rust account row gains GET /player/rust/economics.

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` |
+    | **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) |
 
     #### The gate is `rust`, and `PLAYER` means staff too