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>

internal/handlers/dashboard.go

@@ -24,10 +24,11 @@ func (a *App) GetDashboardRefresh(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	// Render only the inner block by reusing the full body component; the
-	// outer hx-swap="outerHTML" replaces the same wrapper. The full Dashboard
-	// template is overkill but keeps a single source of truth.
-	render(w, r, templates.Dashboard(d))
+	// Render ONLY the inner body. The hx-swap="outerHTML" on DashboardBody's
+	// root div replaces it with this fresh copy. Rendering templates.Dashboard
+	// here would return the whole Layout — sidebar included — nested inside
+	// the div, producing a duplicate nav bar on every refresh.
+	render(w, r, templates.DashboardBody(d))
 }
 
 func (a *App) dashboardData(r *http.Request) (templates.DashboardData, error) {