kiosk: pi-friendly compact mode + chromium 72 fallbacks

- Detect kiosk mode (localhost / ?kiosk=1) and add html.kiosk-mode
- Suppress 3D path-viewer in kiosk mode (Pi 3B too slow)
- Compact 1366x768 layout: 56px header, smaller jog grid, 4-col macros
  2-col status, 540px jog column
- Flex-gap fallbacks for Chromium 72 (header tabs, sys-btn, state-badge,
  ktab, sp-row, etc.) using "> * + *" margin-* rules
- Path-viewer: opaque WebGL canvas, ResizeObserver-gated render loop,
  no first-frame size flash
- Path-viewer renderer cleared properly on component teardown
- W axis row: W- | W+ | Probe XYZ | Probe Z (was W-|HomeW|W+|Probe)
- Running panel only for actual program execution (not jogging)
- Settings sectioned (Display+Units / Probing / G-code+Motion)
- Routed component now keep-alive across tab swaps
- FA4 -> FA6 webfonts

src/js/w-axis-view.js

@@ -0,0 +1,20 @@
+"use strict";
+
+// V09 W-axis page \u2014 mounts the existing WAxisSettings Svelte component
+// inside the settings shell so it gets a real top-level rail entry
+// instead of being a soft-link anchor inside Display & Units.
+
+module.exports = {
+    template: "#w-axis-view-template",
+
+    attached: function () {
+        this.svelteComponent = SvelteComponents.createComponent(
+            "WAxisSettings",
+            document.getElementById("w-axis-mount")
+        );
+    },
+
+    detached: function () {
+        if (this.svelteComponent) this.svelteComponent.$destroy();
+    },
+};