Token auto-discovery, tx history, balance polling, EIP-6963, UI overhaul

Major changes:
- Fetch token balances and tx history from Blockscout API (configurable)
- Remove manual token discovery (discoverTokens) in favor of Blockscout
- HD address gap scanning on mnemonic import
- Duplicate mnemonic detection on wallet add
- EIP-6963 multi-wallet discovery + selectedAddress updates in inpage
- Two-tier balance refresh: 10s while popup open, 60s background
- Fix $0.00 flash before prices load (return null when no prices)
- No-layout-shift: min-height on total value element
- Aligned balance columns (42ch address width, consistent USD column)
- All errors use flash messages instead of off-screen error divs
- Settings gear in global title bar, add-wallet moved to settings pane
- Settings wells with light grey background, configurable Blockscout URL
- Consistent "< Back" buttons top-left on all views
- Address titles (Address 1.1, 1.2, etc.) on main and detail views
- Send view shows current balance of selected asset
- Clickable affordance policy added to README
- Shortened mnemonic backup warning
- Fix broken background script constant imports

src/popup/views/confirmTx.js

@@ -8,10 +8,7 @@ const { state } = require("../../shared/state");
 const { getSignerForAddress } = require("../../shared/wallet");
 const { decryptWithPassword } = require("../../shared/vault");
 const { formatUsd, getPrice } = require("../../shared/prices");
-const {
-    getProvider,
-    invalidateBalanceCache,
-} = require("../../shared/balances");
+const { getProvider } = require("../../shared/balances");
 const { isScamAddress } = require("../../shared/scamlist");
 
 let pendingTx = null;
@@ -163,12 +160,19 @@ function init(ctx) {
             });
             statusEl.textContent = "Sent. Waiting for confirmation...";
             const receipt = await tx.wait();
-            statusEl.textContent =
-                "Confirmed in block " +
-                receipt.blockNumber +
-                ". Tx: " +
-                receipt.hash;
-            invalidateBalanceCache();
+            statusEl.innerHTML = "";
+            statusEl.appendChild(
+                document.createTextNode(
+                    "Confirmed in block " + receipt.blockNumber + ". Tx: ",
+                ),
+            );
+            const link = document.createElement("a");
+            link.href = "https://etherscan.io/tx/" + receipt.hash;
+            link.target = "_blank";
+            link.rel = "noopener";
+            link.className = "underline decoration-dashed break-all";
+            link.textContent = receipt.hash;
+            statusEl.appendChild(link);
             ctx.doRefreshAndRender();
         } catch (e) {
             statusEl.textContent = "Failed: " + (e.shortMessage || e.message);