feat(web): slim the list filters and hide them when empty

At current scale the date-range pickers are dead weight (UX review C1/C2):

- Drop the From/To date inputs from the filter bar; keep the Channel field and
  the "Summarized only" toggle. (Filter still parses from/to for hand-built
  URLs and apply() compatibility — only the UI is removed.)
- Hide the filter bar entirely on a genuinely empty account (no rows AND no
  active filter) so the connect CTA stands alone; a filter that matches nothing
  still shows the bar so it can be cleared.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/web/handlers_test.go

@@ -360,6 +360,22 @@ func TestListCollapsesOlderAndNoCaption(t *testing.T) {
 	require.NotContains(t, html, "No Caption Vid", "caption-less video is collapsed, not a card")
 }
 
+// TestListHidesFilterBarWhenEmpty: a genuinely empty list shows no filter bar
+// (the connect CTA stands alone), but a filter that matches nothing still shows
+// the bar so it can be cleared (UX review C1).
+func TestListHidesFilterBarWhenEmpty(t *testing.T) {
+	app := newApp(t)
+	resetDB(t, rawPool(t))
+
+	rec := do(t, app, httptest.NewRequest(http.MethodGet, "/", nil))
+	require.Equal(t, http.StatusOK, rec.Code)
+	require.NotContains(t, body(t, rec), `class="filters"`, "no filter bar on an empty account")
+
+	rec = do(t, app, httptest.NewRequest(http.MethodGet, "/?channel=nope", nil))
+	require.Equal(t, http.StatusOK, rec.Code)
+	require.Contains(t, body(t, rec), `class="filters"`, "filtered-to-empty keeps the bar so it can be cleared")
+}
+
 func TestRequestSummarizeQueuesAndRendersCard(t *testing.T) {
 	ctx := context.Background()
 	app := newApp(t)