fix: the address screen shows a token just added at its fetched balance, not 0.0000 (closes #516)

A balance refresh that returns now draws the balances on AddressDetail or
AddressToken again when that screen is up, not only the wallet list; their
transaction lists are left alone. Every add path on AddToken and
SettingsAddToken tracks a token through one step, trackToken(), which also
lists it in the new stored field tokensNotFetched: its line reads `quantity
unknown` instead of 0.0000 until a refresh that started with it tracked has
fetched every address's token balances, even if the popup closes first. To
tell an address whose token balances the explorer did not return, the refresh
takes them off its copy of the wallets before fetching.

Model: opus-5-5

tests/e2e/run.js

@@ -651,7 +651,8 @@ test("a token added by its contract address is listed on the address screen (#15
     await visible(env.page, "#view-address");
 
     // No wait: the confirm renders the balance list before it shows the
-    // screen, and nothing renders the list again while the screen is up.
+    // screen. The refresh it starts draws the list again, with the row still
+    // in it.
     const row = env.page.locator(
         '#address-balances [data-token="' + STUB_TOKEN.address + '"]',
         { hasText: STUB_TOKEN.symbol },