feat: remove an address from an HD wallet, behind a confirmation (closes #162)

Address rows on Home now carry an [x] control on wallets that derive their
addresses from an extended key and hold more than one; it opens a
confirmation screen before anything is removed.

Removing an address destroys nothing, and the copy says so: the address stays
derivable from key material the wallet still holds, any funds at it stay
where they are, and importing the recovery phrase brings it back. That is
also why the screen is not password-gated, unlike delete-wallet — a password
gates the disclosure or destruction of a secret, and this does neither. A
balance is surfaced as a warning line, never as a refusal.

The state transition lives next to the wallet one in
src/shared/walletDelete.js and shares its address comparison, site-permission
cleanup and broadcast, so the rules match one level down: the last address of
a wallet is never removable, the selection moves only when it was the address
removed, an index after the splice is decremented, a selection in another
wallet is untouched, and AUTISTMASK_ACTIVE_CHANGED is broadcast when the
active address moves so a connected site stops being told about an address
the user removed.

The wallet's derivation counter is a high-water mark and is not rewound, so
"+" derives a fresh index rather than handing back the address just removed.

README.md

@@ -128,7 +128,9 @@ transaction detail screen for an ERC-20 transfer, and the recovery phrase screen
 — which wallet types are offered it, that it holds nothing before the password
 is accepted, that a wrong password reveals nothing, that leaving it by either
 route wipes it — including a leave taken while the decrypt is still running —
-and that reopening the popup does not land on it. All outbound network is
+and that reopening the popup does not land on it. It also covers address
+removal: which wallets offer the control at all, that leaving the confirmation
+removes nothing, and that confirming it does. All outbound network is
 intercepted at the browser level and served from fixtures in
 `tests/e2e/network.js`, so the run is deterministic and fully offline;
 unrecognised outbound requests are reported as failures rather than silently
@@ -508,8 +510,9 @@ of it.
     - Wallet list: each wallet shows its name (tap to rename inline) and a "+"
       button for HD and xprv wallets, then one block per address with "Address
       N" (bold when active), the ENS name if resolved, the full address, an
-      `[info]` button, the address USD total, and a balance line for ETH and for
-      each token shown for that address
+      `[info]` button, an `[x]` button (only on HD and xprv wallets holding more
+      than one address), the address USD total, and a balance line for ETH and
+      for each token shown for that address
     - "Recent Transactions": up to 25 transactions merged across every address
       of every wallet, deduplicated by hash and filtered
     - "Add additional wallet..." link at bottom
@@ -519,6 +522,7 @@ of it.
     - Tap wallet name → inline rename field (no screen change)
     - "+" on wallet → derives the next address inline (no screen change)
     - `[info]` on address → **AddressDetail**
+    - `[x]` on address → **DeleteAddress**
     - "Send" → **Send** (refuses with a flash message on a zero balance)
     - "Receive" → **Receive** (shows active address QR)
     - Tap home tx row → **TransactionDetail**
@@ -869,6 +873,40 @@ of it.
       nothing deleted
     - "Back" → previous screen (Settings)
 
+#### DeleteAddress (`delete-address-confirm`)
+
+- **When**: User tapped the `[x]` next to an address on Home. Offered only on HD
+  and xprv wallets holding more than one address: the last address of a wallet
+  is never removable, and a key wallet has exactly one.
+- **Elements**:
+    - "Back" button, "Remove Address" heading
+    - The address's own label ("Address N") and its wallet's name
+    - The full address (color dot, etherscan link, tap to copy), with the ENS
+      name above it if resolved
+    - Explanation that this only stops the wallet tracking the address: nothing
+      is destroyed, no key is deleted, funds stay where they are, and the
+      address comes back by importing the recovery phrase again
+    - A line naming the address's ETH balance when it holds one, stating that
+      removal moves and spends nothing. A balance is a warning, never a refusal.
+    - The rule that a wallet always keeps at least one address, and that
+      removing the last one means deleting the wallet from Settings
+    - Error line
+    - "Remove Address" button
+- **Transitions**:
+    - "Remove Address" → removes the address and its site permissions, then →
+      previous screen (Home) with an "Address removed." flash message
+    - "Back" → previous screen (Home), nothing removed
+- **Deliberately not password-gated**, unlike DeleteWallet: a password gates the
+  disclosure or destruction of a secret, and this does neither. The address
+  stays derivable from key material the wallet still holds.
+- The active address moves only if it was the address removed, and then to the
+  wallet's first remaining address, with `AUTISTMASK_ACTIVE_CHANGED` broadcast
+  so a connected site stops being told about an address the user removed
+  (`src/shared/walletDelete.js`). A selection in any other wallet is left alone;
+  one in this wallet follows the splice.
+- The wallet's derivation counter (`nextIndex`) is not rewound, so "+" derives a
+  fresh address rather than handing back the one just removed.
+
 #### SettingsAddToken (`settings-addtoken`)
 
 - **When**: User tapped "+ Add token" in Settings. Tokens added here are tracked
@@ -1318,7 +1356,7 @@ Currently supported:
 ### Wallet Management
 
 - [x] Delete wallet (with confirmation)
-- [ ] Delete address from HD wallet (with confirmation)
+- [x] Delete address from HD wallet (with confirmation)
 - [x] Show wallet's recovery phrase (requires password)
 
 ### Transactions