Add transaction confirmation screen and password modal

New send flow: Send → Confirm → Password → Broadcast.

Send view: collects To (with ENS resolution), Amount, Token.
"Review" button advances to confirmation. No password field.

Confirm Transaction view: shows From, To (with ENS name),
Amount (with USD value), and runs pre-send checks:
- Scam address warning (checked against local blocklist)
- Self-send warning
- Insufficient balance error (disables Send button)

Password modal: full-screen overlay, appears only after user
clicks Send on the confirmation screen. Decrypts the wallet
secret, signs and broadcasts the transaction. Wrong password
is caught inline.

scamlist.js: hardcoded set of known scam/fraud addresses
(Tornado Cash sanctioned, drainer contracts, address
poisoning). Checked locally, no external API.

src/popup/views/helpers.js

@@ -9,6 +9,7 @@ const VIEWS = [
     "main",
     "address",
     "send",
+    "confirm-tx",
     "receive",
     "add-token",
     "settings",