feat(ui): render the Weather readout as one component

createWeatherPanel() computes the readout it shows (forecast and event
cards, the observed group's scope, the history timeline state and observed
cards) and renders WeatherReadout synchronously into the panel body, so a
newly opened card is still revealed after measuring. The hand-built hosts
and the separate card and timeline builders are gone; markup, open-card
choice, first appearance and teardown are unchanged.

scripts/package-boundaries.json

@@ -575,7 +575,8 @@
       "src/ui/rail/RailCards.vue",
       "src/ui/rail/utcClock.js",
       "src/ui/rail/RailTimeline.vue",
-      "src/ui/rail/rangeValue.js"
+      "src/ui/rail/rangeValue.js",
+      "src/ui/weather/WeatherReadout.vue"
     ],
     "external": ["vue"]
   },
@@ -942,7 +943,8 @@
       "src/ui/rail/RailCards.vue",
       "src/ui/rail/utcClock.js",
       "src/ui/rail/RailTimeline.vue",
-      "src/ui/rail/rangeValue.js"
+      "src/ui/rail/rangeValue.js",
+      "src/ui/weather/WeatherReadout.vue"
     ],
     "external": ["cesium", "vue", "pinia"]
   },
@@ -2904,7 +2906,8 @@
       "src/ui/rail/RailCardBlocks.vue",
       "src/ui/rail/utcClock.js",
       "src/ui/rail/RailTimeline.vue",
-      "src/ui/rail/rangeValue.js"
+      "src/ui/rail/rangeValue.js",
+      "src/ui/weather/WeatherReadout.vue"
     ],
     "external": [
       "hls.js",