fix(overview): mining addresses visible at 0 balance; drag-reorder always applies

- Address list: a mining-flagged address stays visible even at 0 balance when
  "hide zero balances" is on (payout addresses shouldn't vanish).
- Drag-reorder: persist dense sort orders (0..N-1) for the whole visible list on
  drop via App::reorderAddresses, instead of a pairwise swap that no-ops when both
  rows are still at the default un-ordered state. First drag now always takes
  effect, and explicit order keeps overriding the starred/type/balance sort.
- Tests: 0-balance mining row survives hide-zero; ordered non-favorite outranks a
  favorite.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ui/windows/balance_address_list.cpp

@@ -41,7 +41,8 @@ std::vector<AddressListRow> BuildAddressListRows(const std::vector<AddressListIn
         if (!input.info) continue;
         if (!AddressListMatchesFilter(input, filter)) continue;
         if (input.hidden && !showHidden) continue;
-        if (hideZeroBalances && input.info->balance < 1e-9 && !input.hidden && !input.favorite) continue;
+        // Keep mining-flagged addresses visible even at 0 balance (they receive payouts).
+        if (hideZeroBalances && input.info->balance < 1e-9 && !input.hidden && !input.favorite && !input.mining) continue;
         rows.push_back({input.info, input.isZ, input.hidden, input.favorite, input.mining,
                         input.label, input.icon, input.sortOrder});
     }