fix(core): refresh transaction history on the Mining tab

The Mining tab shows earnings derived from transaction history, but it
was not treated as a wallet-data page, so newly mined or paid-out
earnings did not appear until the user left the tab and came back. A
coinbase row also changes category in place (immature becomes generate
at maturity, or orphan on a reorg), and the Recent merge kept both the
old and the new row, double-counting the earnings.

- The Mining tab now gets the cheap between-blocks Recent poll: one
  listtransactions per new block, bounded by the 15 s transaction-age
  timer, once history has loaded. It never runs a full routine scan and
  never pre-empts an owed dirty cycle; tracked sends still take their
  normal cycle on any page.
- The shielded-payout probe runs only while the pool miner is running,
  since pool payouts are shielded receives while a solo miner's earnings
  are transparent coinbase rows.
- The Recent merge drops the previous row of the other coinbase category
  when a coinbase transitions, so maturing or reorged rewards are no
  longer counted twice. A non-coinbase row sharing the txid is left
  alone.

Behaviour change: mining earnings update on the Mining tab per block
instead of only on tab re-entry, and maturing or reorged coinbase rows
no longer double-count.

Tests: the per-block poll gate (one poll per block, due only after
history loads, held while dirty or addresses are dirty), the Mining-page
cycle shaping, and the coinbase transition merge for immature to
generate, generate to orphan, and a shared-txid non-coinbase row.

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

src/services/history_scan_policy.cpp

@@ -193,5 +193,20 @@ TxCycle decideTxCycle(const TxCycleInputs& in)
     return TxCycle::None;
 }
 
+TxCycleInputs shapeTxCycleForMiningPage(TxCycleInputs in)
+{
+    if (!in.sendTracking) {        // tracked sends need their Light cycle at a new tip, wherever the user is
+        in.newTip = false;
+        in.routineScanWork = false;
+    }
+    return in;
+}
+
+bool miningTxPollDue(const MiningTxPollInputs& in)
+{
+    return in.historyLoaded && in.tip > 0 && in.tip != in.lastPolledTip && in.txAgeDue && !in.dirty &&
+           !in.addressesDirty;
+}
+
 }  // namespace services
 }  // namespace dragonx