[client/ui] Replace fyne UI with Wails (rename ui-wails to ui)

Removes the legacy fyne-based client/ui implementation and renames the
Wails replacement (client/ui-wails) to take its place at client/ui. Go
imports, frontend bindings, CI workflows, goreleaser configs and the
windows .syso icon path are updated to follow the rename.

client/ui/build/appicon.icon/Assets/wails_icon_vector.svg

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!--
+  macOS Icon Composer source. icon.json references this SVG by name and
+  applies its own scale/translation/fill, so we leave the artwork in its
+  native 31×23 viewBox.
+-->
+<svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="0 0 31 23">
+  <path d="M21.4631 0.523438C17.8173 0.857913 16.0028 2.95675 15.3171 4.01871L4.66406 22.4734H17.5163L30.1929 0.523438H21.4631Z" fill="#F68330"/>
+  <path d="M17.5265 22.4737L0 3.88525C0 3.88525 19.8177 -1.44128 21.7493 15.1738L17.5265 22.4737Z" fill="#F68330"/>
+  <path d="M14.9236 4.70563L9.54688 14.0208L17.5158 22.4747L21.7385 15.158C21.0696 9.44682 18.2851 6.32784 14.9236 4.69727" fill="#F05252"/>
+</svg>

client/ui/build/appicon.icon/icon.json

@@ -0,0 +1,51 @@
+{
+  "fill" : {
+    "automatic-gradient" : "extended-gray:1.00000,1.00000"
+  },
+  "groups" : [
+    {
+      "layers" : [
+        {
+          "fill-specializations" : [
+            {
+              "appearance" : "dark",
+              "value" : {
+                "solid" : "srgb:0.92143,0.92145,0.92144,1.00000"
+              }
+            },
+            {
+              "appearance" : "tinted",
+              "value" : {
+                "solid" : "srgb:0.83742,0.83744,0.83743,1.00000"
+              }
+            }
+          ],
+          "image-name" : "wails_icon_vector.svg",
+          "name" : "wails_icon_vector",
+          "position" : {
+            "scale" : 1.25,
+            "translation-in-points" : [
+              36.890625,
+              4.96875
+            ]
+          }
+        }
+      ],
+      "shadow" : {
+        "kind" : "neutral",
+        "opacity" : 0.5
+      },
+      "specular" : true,
+      "translucency" : {
+        "enabled" : true,
+        "value" : 0.5
+      }
+    }
+  ],
+  "supported-platforms" : {
+    "circles" : [
+      "watchOS"
+    ],
+    "squares" : "shared"
+  }
+}