Add pre-submit consent gate for amounts exceeding auto-pay approval

Symmetric across both bridge directions, checked in priority order before
any funds move:
1. Real reserve exceeded (withdrawal only) - the multisig doesn't hold
   enough real USDT on Polkadot Asset Hub. No signature can fix this, so
   this stays a hard block (existing bridge_wusdt_to_usdt_blocked message),
   never offered as "proceed anyway".
2. Automation-key approval exceeded (either direction) - funds exist, the
   automation key just isn't currently approved to auto-pay that much.
   Resolvable by 3-of-5 signing, so this is now an explicit opt-in: a
   warning banner names the ~2h typical review window and the signatories'
   contact channel (t.me/pezkuwidestek), gated behind a WarningCheckBox the
   user must tick before Swap re-enables. Previously there was no signal at
   all here - a large amount would just silently queue for manual review
   after debiting the user, with no way to know that going in.

Both getWusdtRemainingAllowance/getPolkadotUsdtRemainingAllowance query the
real on-chain Assets.Approvals amount per leg - not a guess. Confirmed
on-chain (2026-07-16) the Polkadot leg has never had an approval granted at
all, so every wUSDT->USDT withdrawal currently hits the consent gate
regardless of amount, symmetric with what happens once a signatory grants
one (mirrors the existing wUSDT-side renewal flow exactly, including the
same 40,000/200,000 20%-threshold pattern) - added a second sign button so
a signatory can actually grant it from this screen.

swapClicked()'s confirmation gate now also enforces the consent requirement
server-side (well, client-domain-side) rather than only via the button's
enabled look, consistent with how it already re-checks balance/reserve.

common/src/main/res/values/strings.xml

@@ -365,6 +365,8 @@
     <string name="bridge_below_minimum">Amount below minimum</string>
     <string name="bridge_enter_amount">Enter amount</string>
     <string name="bridge_wusdt_to_usdt_blocked">This amount exceeds the bridge\'s current available reserve (%s USDT). Try a smaller amount.</string>
+    <string name="bridge_consent_required_message">This amount exceeds the automatic payout limit and needs approval from 3 of the bridge\'s 5 signatories - typically resolved within about 2 hours. You can reach them at t.me/pezkuwidestek in the meantime.</string>
+    <string name="bridge_consent_checkbox_label">I understand this may take time to complete and want to proceed</string>
 
     <string name="bridge_sign_status_ok">Bridge allowance OK (%s)</string>
     <string name="bridge_sign_button">Sign renewal (%s)</string>