feat(ui-calculator): input validation, load caps, ceil display, modernization layout

- custom load capped at cargo capacity (error when exceeded); full load shows the cargo capacity; zero cargo pins load to empty and disables the toggle

- per-input red border + tooltip for every invalid value (blocks, techs, load, MAT, modernization target); no value may be negative; locking a speed is disabled when drive is zero

- display every computed number (results + goal-seek back-solved input) rounded up to 3 decimals via a shared pkg/calc Ceil3 bridged to wasm; engine keeps its own round-to-nearest util.Fixed*

- modernization total upgrade cost spans two columns (single line)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/wasm/main.go

@@ -86,6 +86,7 @@ func main() {
 		"shieldsForDefence":  js.FuncOf(shieldsForDefence),
 		"cargoForEmptyMass":  js.FuncOf(cargoForEmptyMass),
 		"loadForFullMass":    js.FuncOf(loadForFullMass),
+		"ceil3":              js.FuncOf(ceil3),
 	}))
 
 	// Block forever so the Go runtime stays alive while JS keeps calling
@@ -420,6 +421,15 @@ func loadForFullMass(_ js.Value, args []js.Value) any {
 	return js.ValueOf(v)
 }
 
+// ceil3 bridges `calc.Ceil3`. Input `{ value }`, output a JS number
+// rounded up to three decimal places.
+func ceil3(_ js.Value, args []js.Value) any {
+	if len(args) != 1 {
+		return js.Null()
+	}
+	return js.ValueOf(calc.Ceil3(args[0].Get("value").Float()))
+}
+
 // copyBytesFromJS materialises a JS Uint8Array (or any indexable
 // byte-shaped value) into a Go byte slice. We avoid `js.CopyBytesToGo`
 // because TinyGo's implementation panics on values it does not