BankSeller 1.0.3: support F2P trade-restricted accounts

[Joinkiee]

Updates the Bank Seller plugin to 1.0.3, tested live on a new F2P trade-restricted account.

What changed

• F2P trade restriction handling: the per-item "restricted for trading" notice is read straight from the sell offer setup. Restricted items are skipped by clicking the next inventory item inside the setup - the GE window is never closed between items, and refused items are put back in the bank.
• Instant-sell pricing: every offer is listed at 50% of the actively traded price so it fills immediately.
• Full stacks: each item's whole quantity goes into a single offer.
• Leftover-offer liquidation: if an offer has not sold by the end (90s idle), it is aborted, collected and re-listed at 1gp so the run can finish. The plugin then collects and disables itself.
• Clean finish: pending offers are watched client-side (no mouse churn), coins are collected, and a single chatbox verdict is shown when the bank is fully processed - an explicit error when the GE refused everything.
• Coins and platinum tokens are never sold; bank/GE open failures retry instead of falsely concluding the bank is empty.

Only files under bankseller/ (plus its docs readme) are touched.

Testing steps

1. Build with ./gradlew build -PpluginList=BankSellerPlugin (JDK 11, client 2.6.19).
2. On a new F2P trade-restricted account with assorted bank items, start the plugin next to the GE bank booth.
3. Restricted items (e.g. Shrimps) are detected from the offer setup in ~1s each and skipped without the GE window closing; sellable items are listed at -50% and fill immediately.
4. At the end the plugin idles while offers sell, re-lists any unsold leftover at 1gp, collects, prints the final chatbox verdict and disables itself.
5. Verified: 42 offers placed/sold and 9 restricted items skipped in one live session with no stuck state.

[chsami]

Thanks — the build and live-session results look good, but I found one merge-blocking safety issue in the forced-liquidation path.

In BankSellerScript.liquidateLeftoverOffers(), Rs2GrandExchange.abortAllOffers(false) aborts every occupied GE offer, not just offers created by BankSeller. The subsequent sellInventory() call can then include contents collected from unrelated offers and re-list them at 1 gp. Please either track the slots/items owned by this run and abort only those, or refuse to start unless all GE slots are empty (the owned-offer approach is safer). Completed unrelated offers should likewise not be collected into the liquidation inventory.

There is also a smaller reliability issue in placeSellOffer(): when the offer setup never opens, !offerSetupSeen exits the retry loop and the caller permanently marks that item unsellable. A transient widget/UI timeout should be retried and should not populate unsellableItemIds; only the explicit trade-restriction message should do that.

Once those paths are isolated from pre-existing offers and transient failures, this should be in much safer shape to merge.