Add SwapParams.wait_for_all_submits to restore all-routes signature collection

v4.0.11 switched the fast-submit (`wait_tx_confirmed = false`) result loop
from `wait_for_all_submitted` to `wait_for_first_submitted`. The new
function returns as soon as one SWQOS route's HTTP submit completes and
drains whatever signatures are in `ResultCollector.results` at that
moment — slower routes' signatures arrive after the caller has returned.

This is correct for fire-and-forget low-latency submits, but breaks
callers that do their own on-chain confirmation against a pinned durable
nonce. Only one of the submitted txs can land (nonce is consumed by
whichever lands first), but the caller has no way of knowing in advance
which route it will be. Their post-submit logic feeds every returned
signature to `getSignatureStatuses` to find the landed one — with only
the fastest HTTP responder returned (often not the one that lands), the
landed tx isn't in the polled set.

Adds an opt-in `SwapParams.wait_for_all_submits: bool` (default false,
plumbed through `TradeBuyParams` / `TradeSellParams`). When true and
`wait_tx_confirmed = false`, `execute_parallel` uses
`wait_for_all_submitted` (still in the codebase, was
`#[allow(dead_code)]`) so every submitted signature is returned. Zero
behaviour change for current users.

src/trading/core/params/dex_swap.rs

@@ -82,6 +82,14 @@ pub struct SwapParams {
     pub simulate: bool,
     /// Whether to output SDK logs (from TradeConfig.log_enabled).
     pub log_enabled: bool,
+    /// Fast-submit only (`wait_tx_confirmed = false`): when true, wait for every
+    /// SWQOS route's HTTP submit response so all submitted signatures are
+    /// returned. Defaults to false (post-4.0.11 behaviour: return after the
+    /// first route accepts). Set to true when the caller does its own on-chain
+    /// confirmation against a pinned durable nonce — only one route's tx can
+    /// land, but the caller cannot know which in advance, so it needs every
+    /// signature to poll via `getSignatureStatuses`.
+    pub wait_for_all_submits: bool,
     /// Use dedicated sender threads (internal; set via client.with_dedicated_sender_threads()).
     pub use_dedicated_sender_threads: bool,
     /// Core indices for dedicated sender threads (from TradeConfig.sender_thread_cores). Arc avoids cloning the Vec on hot path.