fix(lite): refresh the sidebar unconfirmed badge on confirmations

The sidebar unconfirmed-tx badge was recomputed only when the tx list
changed, keyed on last_tx_update plus the list size. That missed the
one case that matters most: a transaction confirming without the list
count changing. last_tx_update did not move for a same-second content
change, and lite never stamped it at all, so the badge stuck on a
stale 0-conf count until some unrelated refresh happened to shift the
list size.

- The badge now keys on tx_revision, which the state bumps on every
  content change - including a confirmation flip at an unchanged tx
  count - and which lite stamps too, so the count tracks confirmations
  on both the full node and the lite wallet.
- The sentinel starts at 0, which tx_revision never takes (it starts
  at 1), so the first frame always computes once.
- The recompute still runs only when the revision actually moved, so
  the per-frame work the previous guard avoided is still avoided.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app.h

@@ -1006,10 +1006,9 @@ private:
     mutable std::uint64_t chat_unread_rev_ = ~0ull;   // ~0 forces the first compute
     mutable int    chat_unread_cached_ = 0;
     mutable double chat_unread_computed_at_ = 0.0;
-    // Sidebar unconfirmed-tx badge — recomputed only when the tx list changes (keyed on last_tx_update +
-    // size), not every frame. See App::render().
-    std::int64_t sb_unconf_key_ts_ = -1;
-    std::size_t  sb_unconf_key_n_  = 0;
+    // Sidebar unconfirmed-tx badge — recomputed only when the tx list changes (keyed on tx_revision),
+    // not every frame. See App::render().
+    std::uint64_t sb_unconf_key_rev_ = 0;   // sentinel 0 never matches: tx_revision starts at 1
     int          sb_unconf_count_  = 0;
     // Daemon-memory probe is expensive (/proc scan on Linux, popen on macOS): it runs on this sampler's own
     // thread, at most once per 3 s and only while a reader asks (Mining tab memory bar, Peers tab Memory cell).