feat(panel): lay a delivery's log lines out as a table

The lines came out as one block of preformatted text, which is what the
system log page does with a tail of mail.log — right there, where the
lines are unrelated to each other and the block is the log itself. Here
they are one message's six or seven lines, and what is read off them is
the pace: the second between the connection and the banner, the ten
between DATA and the reply. Run together, every line began with a
different-width stamp and none of those numbers lined up.

So they are two columns now, when and what, the same shape the send log
itself has. logtail.SplitTimestamp takes the stamp off the head of a
line: postlogd's format, which is what this server writes, and syslog's
traditional one for a deployment that routes the log through syslogd
instead. The stamp loses its microseconds and its offset — five decimal
places are the widest part of the column and the least worth reading —
but is not converted, so the page shows the log's own wall clock rather
than a claim about which zone it was in.

A line whose head is not a stamp either parser recognises keeps its whole
text in the second column and leaves the first empty. The format is the
log's, not ours; a line we cannot split is a line we must not drop, and
the test says so.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/web/templates/delivery.html

@@ -98,9 +98,25 @@
   message's queue id are shown; the whole log is on the
   <a href="/system-log">System log</a> page.</p>
 
-  {{if .LogLines}}
-  <span class="code">{{range .LogLines}}{{.}}
-{{end}}</span>
+  {{if .LogRows}}
+  {{/* Two columns, the way the send log itself is a table: the times down one
+       edge are what the message's pace is read off — the seconds between the
+       connection and the reply — and lining them up is what makes that
+       readable. A line whose head was not a timestamp keeps its whole text in
+       the second column and leaves the first empty. */}}
+  <table class="log">
+    <thead>
+      <tr><th>Time</th><th>Message</th></tr>
+    </thead>
+    <tbody>
+      {{range .LogRows}}
+      <tr>
+        <td class="time muted">{{if .Time}}{{.Time}}{{else}}—{{end}}</td>
+        <td class="log-text">{{.Text}}</td>
+      </tr>
+      {{end}}
+    </tbody>
+  </table>
   {{else}}
   <p class="muted">{{.LogNote}}</p>
   {{end}}