open-timestamps: wrap tables in .table-responsive for mobile

Mobile-viewport sweep (375x667 / 390x844 / 412x915) found that the
Calendars and Recent commits tables are 509px wide and were overflowing
past the viewport edge with no internal scroll. Document docW stayed
== visW because an upstream .d-flex has overflow-x: clip, so the right
columns of both tables were silently CLIPPED on every mobile screen
under 509px wide -- users couldn't see the rightmost columns at all
(commits, blocks, calendar URI tail, etc.).

Fix: wrap each <table> in a <div class='table-responsive'> -- Bootstrap's
standard pattern for tables that need horizontal scroll on small screens.
The table itself stays at natural width; the wrapper scrolls.

No code changes needed for the rest of the page: the dropzones, the
hero copy, and the form layout already collapse cleanly via the existing
.col-md-6 breakpoints. The 'DIV.row.g-3' bounding-box overhang seen in
the sweep is Bootstrap's gutter negative-margin artifact (compensated by
.container-xl padding), harmless.

102 _ordpool jest tests pass. AOT prod build clean.

\xf0\x9f\x98\xba

Author: hans-crypto

frontend/src/app/components/_ordpool/open-timestamps/open-timestamps.component.html

@@ -82,6 +82,7 @@ <h2 id="calendars" class="mt-4">Calendars</h2>
   } @else if (calendars.length === 0) {
     <p class="text-muted">No calendar data yet -- the OTS poller is still warming up.</p>
   } @else {
+    <div class="table-responsive">
     <table class="table table-borderless table-striped table-dark">
       <thead>
         <tr>
@@ -110,6 +111,7 @@ <h2 id="calendars" class="mt-4">Calendars</h2>
         }
       </tbody>
     </table>
+    </div>
     <p class="text-muted mt-2">
       Know an active OpenTimestamps calendar that's missing here?
       <a href="https://github.com/ordpool-space/ordpool/edit/main/backend/src/api/explorer/_ordpool/ots-calendars.json"
@@ -131,6 +133,7 @@ <h2 id="recent-commits" class="mt-4">Recent commits</h2>
   } @else if (recent.length === 0) {
     <p class="text-muted">No commits indexed yet.</p>
   } @else {
+    <div class="table-responsive">
     <table class="table table-borderless table-striped table-dark">
       <thead>
         <tr>
@@ -165,5 +168,6 @@ <h2 id="recent-commits" class="mt-4">Recent commits</h2>
         }
       </tbody>
     </table>
+    </div>
   }
 </div>