Update vehicle counts layer to show all years and emphasize data source

src/lib/browse/layers/points/VehicleCounts.svelte

@@ -19,7 +19,7 @@
   let name = "vehicle_counts";
 
   let colorScale = colors.sequential_low_to_high;
-  // Manual buckets for motor_vehicles_2022, which max out at 205,000
+  // Manual buckets for motor_vehicles, which max out at 205,000
   let limits = [0, 40000, 80000, 120000, 160000, 205000];
   // Remove some because there's not much width
   let describeLimits = ["", "40k", "80k", "120k", "160k", ""];
@@ -41,21 +41,23 @@
   <span slot="right">
     <HelpButton>
       <p>
-        2022 AADF (annual average daily flow) data from <ExternalLink
+        AADF (annual average daily flow) data from <ExternalLink
           href="https://roadtraffic.dft.gov.uk/downloads"
         >
           DfT road statistics
         </ExternalLink>. This counts the total daily number of vehicles
         traveling past a count point (in both directions) on an average day of
-        the year. See <ExternalLink
+        the year. Data from the latest year available is shown. See <ExternalLink
           href="https://storage.googleapis.com/dft-statistics/road-traffic/all-traffic-data-metadata.pdf"
         >
           methodology
         </ExternalLink> for details and caveats about the measurements.
       </p>
       <p>
-        The colors show motor vehicles AADF, not pedal cycles. Click a point for
-        full data.
+        The colors show motor vehicles AADF, not pedal cycles. The outline is
+        thicker when the latest data is a manual or automatic count, and thinner
+        when it's an estimate from previous years or nearby counters. Click a
+        point for full data.
       </p>
       <OsOglLicense />
     </HelpButton>
@@ -73,7 +75,7 @@
     sourceLayer={name}
     paint={{
       "circle-color": makeColorRamp(
-        ["get", "motor_vehicles_2022"],
+        ["get", "motor_vehicles"],
         limits,
         colorScale,
       ),
@@ -90,7 +92,16 @@
         15,
       ],
       "circle-stroke-color": "black",
-      "circle-stroke-width": 0.1,
+      "circle-stroke-width": [
+        "case",
+        [
+          "in",
+          ["get", "method"],
+          ["literal", ["Manual count", "Automatic counter"]],
+        ],
+        1.5,
+        0.1,
+      ],
     }}
     layout={{
       visibility: show ? "visible" : "none",
@@ -102,13 +113,15 @@
     <Popup let:props>
       <h2>{props.location}</h2>
       <p>
-        Total motor vehicles (2022 AADF): <b>
-          {props.motor_vehicles_2022.toLocaleString()}
+        Total motor vehicles ({props.year} AADF):
+        <b>
+          {props.motor_vehicles.toLocaleString()}
         </b>
       </p>
       <p>
-        Total pedal cycles (2022 AADF): <b>
-          {props.pedal_cycles_2022.toLocaleString()}
+        Total pedal cycles ({props.year} AADF):
+        <b>
+          {props.pedal_cycles.toLocaleString()}
         </b>
       </p>
       <p>