Fix bugs found in local testing

- Dashboard auto-refresh rendered the full layout into its own
  refresh container, producing a duplicate sidebar every 60s; it now
  renders only the body partial.
- 'Run Now' runs synchronously with a bounded timeout and returns
  refreshed results plus success/error feedback, instead of
  firing-and-forgetting with no signal.
- Price-history chart data moved from a <script> block to a data-
  attribute: templ does not interpolate expressions inside <script>
  element content, so the JSON was emitted literally.
- The htmx indicator spinner was permanently visible due to CSS
  source order; the indicator rules now follow .v-spinner.

Also refreshes README for this session's changes.

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

static/css/app.css

@@ -193,11 +193,6 @@ table.v-table tr:hover td { background: rgba(255,255,255,0.03); }
   margin-bottom: 1rem;
 }
 
-/* htmx indicator: hidden by default, visible during in-flight requests. */
-.htmx-indicator { display: none; }
-.htmx-request .htmx-indicator,
-.htmx-request.htmx-indicator { display: inline-flex; }
-
 .v-spinner {
   display: inline-block;
   width: 14px; height: 14px;
@@ -207,3 +202,11 @@ table.v-table tr:hover td { background: rgba(255,255,255,0.03); }
   animation: v-spin 0.8s linear infinite;
 }
 @keyframes v-spin { to { transform: rotate(360deg); } }
+
+/* htmx indicator: hidden by default, visible during in-flight requests.
+   Declared AFTER .v-spinner on purpose: an element carrying both classes
+   (e.g. <span class="v-spinner htmx-indicator">) must stay hidden until a
+   request is active, and equal-specificity rules resolve by source order. */
+.htmx-indicator { display: none; }
+.htmx-request .htmx-indicator,
+.htmx-request.htmx-indicator { display: inline-flex; }