harden: end a site's unremembered connection when its address or wallet is removed (closes #245)

A site connected without "Remember" lives only in the background's
in-memory connectedSites map. Removing an address or deleting a wallet
dropped the remembered permissions but never told the background; the
entry went only as a side effect of the accountsChanged broadcast, which
empties the whole map when the active address changes.

dropSitePermissions(), shared by both removal paths, now sends
AUTISTMASK_ADDRESSES_REMOVED with the removed addresses, and the
background deletes their entries. Only the extension's own pages may
send it.

Model: opus-5-5

README.md

@@ -1646,6 +1646,10 @@ view would leave a wallet one click from deletion.
     - Either way, the active address moves only if it belonged to the deleted
       wallet, and `AUTISTMASK_ACTIVE_CHANGED` is broadcast when it does
       (`src/shared/walletDelete.js`)
+    - Either way, every address the wallet held loses its site permissions of
+      both kinds: the remembered ones in storage, and the connections approved
+      without "Remember", which only the background holds, in memory, and drops
+      on `AUTISTMASK_ADDRESSES_REMOVED`
     - "Confirm Delete" (wrong password) → "That password is incorrect. Please
       try again." on the error line, nothing deleted
     - "I have lost my password" → **DeleteWalletLostPassword**
@@ -1742,6 +1746,10 @@ view would leave a wallet one click from deletion.
   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 address loses its site permissions of both kinds, whether or not it was
+  the active one: the remembered ones in storage, and any connection approved
+  without "Remember", which only the background holds, in memory, and drops on
+  `AUTISTMASK_ADDRESSES_REMOVED`.
 - The wallet's derivation counter (`nextIndex`) is not rewound, so "+" derives a
   fresh address rather than handing back the one just removed.