UI: render W (aux) axis row in the main DRO

Adds the auxcnc W axis to the front-page Position table:

- axis-vars.js exposes a 'w' computed property fed by state.aux_pos /
  aux_enabled / aux_homed / aux_present (set by AuxAxis on the host).
  No motor mapping, no soft-limit warnings - the aux controller does
  its own bounds.
- control-view.pug adds a W row after the xyzabc loop. The Set/Zero
  button calls /api/aux/set-zero {mm:0} and the Home button calls
  /api/aux/home, which hit the new endpoints exposed by Web.py.
- control-view.js: aux_home(), aux_set_zero(), and aux_jog() helpers.

When aux_enabled is false (no aux.json or aux.json has enabled=false)
the row stays hidden, matching the existing axis-row behavior.

src/js/axis-vars.js

@@ -32,6 +32,10 @@ module.exports = {
             return this._compute_axis("c");
         },
 
+        w: function() {
+            return this._compute_aux_axis();
+        },
+
         axes: function() {
             return this._compute_axes();
         }
@@ -203,6 +207,52 @@ module.exports = {
             return false;
         },
 
+        _compute_aux_axis: function() {
+            // Virtual W axis driven by the auxcnc ESP32. Position, homed
+            // flag and presence come from the bbctrl AuxAxis driver via
+            // state.aux_*. No motor mapping, no soft-limit warnings on
+            // toolpath bounds (auxcnc enforces its own).
+            const enabled = !!this.state.aux_enabled;
+            const present = !!this.state.aux_present;
+            const homed   = !!this.state.aux_homed;
+            const pos     = this.state.aux_pos || 0;
+
+            let klass = `${homed ? "homed" : "unhomed"} axis-w`;
+            let state = present ? "UNHOMED" : "OFFLINE";
+            let icon  = present ? "question-circle" : "plug";
+            let title = present
+                ? "Click the home button to home W axis."
+                : "Aux controller not connected on /dev/ttyUSB0.";
+            if (homed) {
+                state = "HOMED";
+                icon  = "check-circle";
+                title = "W axis successfully homed.";
+            } else if (!present) {
+                klass += " error";
+            }
+
+            return {
+                pos: pos,
+                abs: pos,
+                off: 0,
+                min: 0, max: 0, dim: 0,
+                pathMin: 0, pathMax: 0, pathDim: 0,
+                motor: -1,
+                enabled: enabled,
+                homingMode: "limit-switch",
+                homed: homed,
+                klass: klass,
+                state: state,
+                icon: icon,
+                title: title,
+                ticon: "check-circle",
+                tstate: "OK",
+                toolmsg: "W axis is not constrained by tool path bounds.",
+                tklass: `${homed ? "homed" : "unhomed"} axis-w`,
+                isAux: true,
+            };
+        },
+
         _compute_axes: function() {
             let homed = false;
 

src/js/control-view.js

@@ -765,6 +765,24 @@ module.exports = {
       api.put(`home/${axis}/clear`);
     },
 
+    aux_home: function () {
+      api.put("aux/home").catch(function (err) {
+        console.error("W home failed:", err);
+      });
+    },
+
+    aux_set_zero: function () {
+      api.put("aux/set-zero", { mm: 0 }).catch(function (err) {
+        console.error("W set-zero failed:", err);
+      });
+    },
+
+    aux_jog: function (delta_mm) {
+      api.put("aux/jog", { mm: delta_mm }).catch(function (err) {
+        console.error("W jog failed:", err);
+      });
+    },
+
     show_set_position: function (axis) {
       SvelteComponents.showDialog("SetAxisPosition", { axis });
     },

src/pug/templates/control-view.pug

@@ -191,6 +191,28 @@ script#control-view-template(type="text/x-template")
                   button.pure-button(:disabled="!is_idle", @click=`home('${axis}')`,
                     title=`Home {{'${axis}' | upper}} axis.`, style="height:60px;width:60px")
                     .fa.fa-home
+
+            // Auxiliary W axis (auxcnc ESP32 over /dev/ttyUSB0)
+            tr.axis(:class="w.klass", v-if="w.enabled", :title="w.title")
+              th.name w
+              td.position: unit-value(:value="w.pos", precision=4)
+              td.absolute: unit-value(:value="w.abs", precision=3)
+              td.offset —
+              td.state
+                .fa(:class="'fa-' + w.icon")
+                | {{w.state}}
+              td.tstate(:class="w.tklass", :title="w.toolmsg")
+                .fa(:class="'fa-' + w.ticon")
+                | {{w.tstate}}
+
+              th.actions
+                button.pure-button(title="Set W axis position to 0.",
+                  @click="aux_set_zero()", style="height:60px;width:60px")
+                  .fa.fa-map-marker
+
+                button.pure-button(:disabled="!w.enabled", @click="aux_home()",
+                  title="Home W axis.", style="height:60px;width:60px")
+                  .fa.fa-home
       
       tr(style="vertical-align: top;")
         td