fix(live-state): eliminate flash on poll by switching to innerHTML swap

outerHTML removes and re-inserts the section on each tick, causing a
blank frame. Keeping the <section> as a stable DOM container and
swapping only innerHTML means avatars and text update in-place without
any teardown/reconstruct cycle.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

l4d2web/templates/_live_state.html

@@ -1,11 +1,7 @@
-<section class="panel live-state"
+<h2 class="section-title">Live state</h2>
-         hx-get="/servers/{{ server.id }}/live-state"
+{% if not snapshot or not snapshot_fresh %}
-         hx-trigger="every {{ poll_seconds }}s"
-         hx-swap="outerHTML">
-  <h2 class="section-title">Live state</h2>
-  {% if not snapshot or not snapshot_fresh %}
   <p class="muted">No data — server is not currently reporting.</p>
-  {% else %}
+{% else %}
   <p class="server-live-summary">
     {{ snapshot.players }}/{{ snapshot.max_players }}
     {% if snapshot.hibernating %}· idle{% endif %}
@@ -14,9 +10,9 @@
       polled {{ ((now - snapshot.last_seen_at).total_seconds() | int) }}s ago
     </small>
   </p>
-  {% endif %}
+{% endif %}
 
-  {% if current_players %}
+{% if current_players %}
   <h3 class="section-subtitle">Current players</h3>
   <ul class="player-grid">
     {% for session, profile in current_players %}
@@ -38,9 +34,9 @@
       </li>
     {% endfor %}
   </ul>
-  {% endif %}
+{% endif %}
 
-  {% if recent_players %}
+{% if recent_players %}
   <h3 class="section-subtitle">Recent players</h3>
   <ul class="player-grid recent">
     {% for row in recent_players %}
@@ -61,5 +57,4 @@
       </li>
     {% endfor %}
   </ul>
-  {% endif %}
+{% endif %}
-</section>

l4d2web/templates/server_detail.html

@@ -22,7 +22,7 @@
   <section class="panel live-state"
            hx-get="/servers/{{ server.id }}/live-state"
            hx-trigger="load, every 5s"
-           hx-swap="outerHTML">
+           hx-swap="innerHTML">
   </section>
 
   <h2 class="section-title">Files</h2>