feat: add fake trading module with crypto, stocks, forex and gold

Paper trading system with 5 commands (trade_topup, trade_buy,
trade_sell, trade_convert, trade_stats). Supports VN stocks via TCBS,
crypto via CoinGecko, forex via ER-API, and gold via PAX Gold proxy.
Per-user portfolio stored in KV with 60s price caching. 54 new tests.

plans/260414-1457-trading-module/phase-05-wiring.md

@@ -0,0 +1,67 @@
+---
+phase: 5
+title: "Integration Wiring"
+status: Pending
+priority: P2
+effort: 15m
+depends_on: [4]
+---
+
+# Phase 5: Integration Wiring
+
+## Overview
+
+Two one-line edits to register the trading module in the bot framework.
+
+## File changes
+
+### `src/modules/index.js`
+
+Add one line to `moduleRegistry`:
+
+```js
+export const moduleRegistry = {
+  util: () => import("./util/index.js"),
+  wordle: () => import("./wordle/index.js"),
+  loldle: () => import("./loldle/index.js"),
+  misc: () => import("./misc/index.js"),
+  trading: () => import("./trading/index.js"),  // <-- add
+};
+```
+
+### `wrangler.toml`
+
+Append `trading` to MODULES var:
+
+```toml
+[vars]
+MODULES = "util,wordle,loldle,misc,trading"
+```
+
+### `.env.deploy` (manual — not committed)
+
+User must also add `trading` to MODULES in `.env.deploy` for the register script to pick up public commands.
+
+## Implementation steps
+
+1. Edit `src/modules/index.js` — add `trading` entry
+2. Edit `wrangler.toml` — append `,trading` to MODULES
+3. Run `npm run lint` to verify
+4. Run `npm test` to verify existing tests still pass (trading tests in Phase 6)
+
+## Verification
+
+- `npm test` — all 56 existing tests pass
+- `npm run lint` — no errors
+- `npm run register:dry` — trading commands appear in output
+
+## Rollback
+
+Remove `trading` from both files. Existing KV data becomes inert (never read).
+
+## Success criteria
+
+- [ ] `src/modules/index.js` has trading entry
+- [ ] `wrangler.toml` MODULES includes trading
+- [ ] Existing tests pass unchanged
+- [ ] Lint passes