feat(ui): large-wallet nudge as a one-time toast + clickable alert

Extend the wallet-bloat warning beyond the Settings banner: when wallet.dat
first crosses 500 MB (full-node, synced), fire a one-time warning toast plus a
clickable "Consolidate notes…" entry in the bell/alerts panel that opens Merge
to Address. The persisted large_wallet_warned flag keeps it once-only and
re-arms if the file later shrinks back under the threshold.

- AlertRecord gains an optional onClick + actionHint; Notifications::action()
  pushes a toast and a clickable history entry. renderAlertHistoryPanel() now
  renders the accent action link (under the message) and measures true content
  height so wrapped messages + the link aren't clipped.
- App::maybeWarnLargeWallet() (mirrors maybeRemindSeedBackup) runs once per
  launch from update(); reuses the existing wallet_size_warn/consolidate strings.

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

src/config/settings.h

@@ -330,6 +330,10 @@ public:
     bool getSeedBackupReminded() const { return seed_backup_reminded_; }
     void setSeedBackupReminded(bool v) { seed_backup_reminded_ = v; }
 
+    // One-time nudge when wallet.dat grows past the bloat threshold (re-armed if it shrinks back).
+    bool getLargeWalletWarned() const { return large_wallet_warned_; }
+    void setLargeWalletWarned(bool v) { large_wallet_warned_ = v; }
+
     // Wallet filenames for which the one-time "this wallet is empty but a sibling holds funds"
     // warning has been dismissed. Keyed per active wallet file so switching to a different empty
     // wallet can warn again (see App::maybeWarnEmptyWalletWithFundedSiblings).
@@ -597,6 +601,7 @@ private:
     std::map<std::string, AddressMeta> address_meta_;
     bool wizard_completed_ = false;
     bool seed_backup_reminded_ = false;
+    bool large_wallet_warned_ = false;
     std::set<std::string> empty_wallet_warning_acked_;  // wallet files whose empty-wallet warning was dismissed
     bool encryption_pending_ = false;
     long long daemon_update_prompted_size_ = 0;  // bundled daemon size last offered via the update prompt