fix(views): wrap My Files table for mobile horizontal scroll

The table at /files was wider than the viewport on iPhone-class widths
(~375 px) — the rightmost column with the Copy and Delete buttons clipped
off-screen with no scroll affordance. Wrapping the table in a
.table-wrap div with overflow-x: auto lets the table scroll within
itself; moving the outer border to the wrapper preserves the desktop
visual unchanged.

- public/style.css: add .table-wrap rule, move border off table, add
  min-width: 100% so the table still fills wide viewports.
- src/views/file-list.ts: wrap <table> in <div class="table-wrap">.
- tests/integration/pages.test.ts: assert rendered HTML contains
  class="table-wrap".

public/style.css

@@ -309,10 +309,16 @@ h1 + p {
   font-size: 12px;
 }
 
+.table-wrap {
+  overflow-x: auto;
+  -webkit-overflow-scrolling: touch;
+  border: var(--border);
+}
+
 table {
   width: 100%;
+  min-width: 100%;
   border-collapse: collapse;
-  border: var(--border);
 }
 
 th {