feat: add wallet deletion from settings (closes #13)

- Per-wallet [delete] links in settings wallet list
- Monochrome styling throughout, no red/danger colors
- Password confirmation modal with warning text
- Cleans up site permissions for deleted addresses
- Switches to first remaining wallet or shows welcome if none left

src/popup/index.html

@@ -842,23 +842,6 @@
                     <div id="settings-denied-sites"></div>
                 </div>
 
-                <div class="border-t border-border-light pt-3 mt-3">
-                    <h3 class="font-bold mb-2">Delete wallet</h3>
-                    <label class="block text-xs text-muted mb-1"
-                        >Select wallet to delete:</label
-                    >
-                    <select
-                        id="delete-wallet-select"
-                        class="border border-border p-1 w-full text-sm bg-bg text-fg mb-2"
-                    ></select>
-                    <button
-                        id="btn-delete-wallet"
-                        class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer"
-                    >
-                        Delete...
-                    </button>
-                </div>
-
                 <div
                     id="delete-wallet-confirm"
                     class="hidden border border-border border-dashed p-3 mt-2 mb-3"