fix(electrum)!: Remove seen_at param from into_tx_graph

and `into_confirmation_time_tx_graph`, since now it makes
sense to use `TxGraph::update_last_seen_unconfirmed`.

Also, use `update_last_seen_unconfirmed` in examples for
electrum/esplora. We show how to update the last seen
time for transactions by calling `update_last_seen_unconfirmed`
on the graph update returned from a blockchain source, passing
in the current time, before applying it to another `TxGraph`.

example-crates/example_esplora/src/main.rs

@@ -189,10 +189,14 @@ fn main() -> anyhow::Result<()> {
             // is reached. It returns a `TxGraph` update (`graph_update`) and a structure that
             // represents the last active spk derivation indices of keychains
             // (`keychain_indices_update`).
-            let (graph_update, last_active_indices) = client
+            let (mut graph_update, last_active_indices) = client
                 .full_scan(keychain_spks, *stop_gap, scan_options.parallel_requests)
                 .context("scanning for transactions")?;
 
+            // We want to keep track of the latest time a transaction was seen unconfirmed.
+            let now = std::time::UNIX_EPOCH.elapsed().unwrap().as_secs();
+            let _ = graph_update.update_last_seen_unconfirmed(now);
+
             let mut graph = graph.lock().expect("mutex must not be poisoned");
             // Because we did a stop gap based scan we are likely to have some updates to our
             // deriviation indices. Usually before a scan you are on a fresh wallet with no
@@ -307,9 +311,13 @@ fn main() -> anyhow::Result<()> {
                 }
             }
 
-            let graph_update =
+            let mut graph_update =
                 client.sync(spks, txids, outpoints, scan_options.parallel_requests)?;
 
+            // Update last seen unconfirmed
+            let now = std::time::UNIX_EPOCH.elapsed().unwrap().as_secs();
+            let _ = graph_update.update_last_seen_unconfirmed(now);
+
             graph.lock().unwrap().apply_update(graph_update)
         }
     };