feat(ui): render the Context mode switch from a store

ContextControls presents the selected mode, the transition busy state and the nearby sites search through a publish option, and ContextView renders them from the gev-context store. ./ui/context stays free of Vue. The Radio QA reads the search button's aria-busy, the state it actually carries.

scripts/package-boundaries.json

@@ -53,6 +53,7 @@
       "src/ui/cctv/CctvPicker.vue",
       "src/ui/stores/cctv.js",
       "src/ui/stores/radio.js",
+      "src/ui/stores/context.js",
       "src/ui/stores/streetLevel.js",
       "src/ui/rail/RailChips.vue",
       "src/ui/views/panels/DisplayPanel.vue",
@@ -967,6 +968,7 @@
       "src/ui/stores/streetLevel.js",
       "src/ui/stores/cctv.js",
       "src/ui/stores/radio.js",
+      "src/ui/stores/context.js",
       "src/ui/stores/display.js"
     ],
     "external": ["cesium", "vue", "pinia"]
@@ -2936,6 +2938,7 @@
       "src/ui/stores/streetLevel.js",
       "src/ui/stores/cctv.js",
       "src/ui/stores/radio.js",
+      "src/ui/stores/context.js",
       "src/ui/stores/display.js"
     ],
     "external": [