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>

templates/dashboard.templ

@@ -34,7 +34,12 @@ type AlertRow struct {
 	FoundAt  time.Time
 }
 
-templ dashboardBody(d DashboardData) {
+// DashboardBody is the self-refreshing inner block. It is both the initial
+// render target (inside Layout) and the response to /dashboard/refresh, so the
+// hx-swap="outerHTML" on its root div replaces it with a fresh copy of itself.
+// GetDashboardRefresh must render THIS, not Dashboard — rendering the full
+// Layout would inject a nested page (and a duplicate sidebar) into the div.
+templ DashboardBody(d DashboardData) {
 	<div hx-get="/dashboard/refresh" hx-trigger="every 60s" hx-swap="outerHTML">
 		<h1 class="text-3xl font-semibold mb-6">Dashboard</h1>
 		<div class="grid grid-cols-2 md:grid-cols-4 gap-4 mb-6">
@@ -111,7 +116,7 @@ templ statCard(label, value, sub string) {
 }
 
 templ Dashboard(d DashboardData) {
-	@Layout(d.Page, dashboardBody(d))
+	@Layout(d.Page, DashboardBody(d))
 }
 
 // Helpers used by multiple templates.