feat: add VNC check, SSH key paste, resources panel, sliders, and self-service billing

- VNC panel auto-hides when VNC is disabled on the server
- SSH key paste textarea at checkout with API key creation during provisioning
- Resources panel with current allocation, traffic progress bar, and upgrade link
- changePackage() now applies individual resource modifications from configurable options
- Order form configurable option dropdowns replaced with styled range sliders
- Self-service billing: credit balance, usage breakdown, credit top-up from client area
- Self-service config options (mode, auto top-off threshold/amount) on products
- Auto top-off via WHMCS cron when credit falls below threshold
- CHANGELOG.md covering all versions from 0.0.6 to present

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

modules/servers/VirtFusionDirect/templates/css/module.css

@@ -139,6 +139,53 @@
     padding: 0.15rem 0.4rem;
 }
 
+/* Resource panel */
+.vf-resource-item .progress {
+    background-color: rgba(0,0,0,0.08);
+    border-radius: 4px;
+}
+
+/* Order form slider UI */
+.vf-slider-container {
+    padding: 8px 0;
+}
+.vf-slider-value {
+    font-weight: 600;
+    font-size: 0.95rem;
+    margin-bottom: 4px;
+    text-align: center;
+}
+.vf-slider {
+    width: 100%;
+    height: 6px;
+    -webkit-appearance: none;
+    appearance: none;
+    background: #ddd;
+    border-radius: 3px;
+    outline: none;
+    cursor: pointer;
+}
+.vf-slider::-webkit-slider-thumb {
+    -webkit-appearance: none;
+    appearance: none;
+    width: 20px;
+    height: 20px;
+    border-radius: 50%;
+    background: #337ab7;
+    cursor: pointer;
+    border: 2px solid #fff;
+    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
+}
+.vf-slider::-moz-range-thumb {
+    width: 20px;
+    height: 20px;
+    border-radius: 50%;
+    background: #337ab7;
+    cursor: pointer;
+    border: 2px solid #fff;
+    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
+}
+
 /* Responsive adjustments */
 @media (max-width: 768px) {
     .vf-power-buttons {