feat(mobile/upload): upload_format setting + Option A local update from server response

Settings → Sync → Upload format: "Original file" (default) / "Extracted JSON".
- raw (default): reads original_path as base64, POSTs to /api/upload/raw; after
  success, overwrites local detail_json/timeseries_json/geojson/source_hash with
  the server's DEM-corrected extraction (Option A). Falls back to bas if the file
  is missing.
- bas: POSTs pre-extracted JSON to /api/upload/bas, faster, no DEM correction.

Switching modes is safe — the server deduplicates by activity id so a previous
raw upload will return status:"duplicate" on a subsequent bas attempt.

mobile/db/sync.ts

@@ -170,6 +170,7 @@ async function uploadLocalActivities(
      FROM activities WHERE origin = 'local' AND synced_at IS NULL`,
   );
 
+  const preferRaw = (await getSetting(db, 'upload_format') ?? 'raw') === 'raw';
   const headers = { Authorization: `Bearer ${token}`, 'Content-Type': 'application/json' };
   let uploaded = 0;
   let failed = 0;
@@ -182,9 +183,10 @@ async function uploadLocalActivities(
     try {
       let resp: Response;
 
-      // Prefer raw upload when the original FIT/GPX/TCX file is still on disk.
-      // The server re-extracts it with DEM elevation correction, producing better data.
-      const useRaw = row.original_path !== null &&
+      // When preferRaw is set and the original file is still on disk, send the raw
+      // bytes to /api/upload/raw so the server re-extracts with DEM elevation correction.
+      const useRaw = preferRaw &&
+        row.original_path !== null &&
         (await FileSystem.getInfoAsync(row.original_path)).exists;
 
       if (useRaw) {
@@ -211,6 +213,38 @@ async function uploadLocalActivities(
 
       if (resp.ok) {
         await db.runAsync(`UPDATE activities SET synced_at = ? WHERE id = ?`, [now, row.id]);
+        // Option A: after a raw upload, update local detail/timeseries/geojson with the
+        // server's DEM-corrected extraction so the app shows better elevation data.
+        if (useRaw) {
+          try {
+            const data = await resp.json() as {
+              id: string;
+              detail: object;
+              timeseries: object | null;
+              geojson: object | null;
+              source_hash: string;
+            };
+            if (data.id === row.id) {
+              await db.runAsync(
+                `UPDATE activities
+                 SET detail_json      = ?,
+                     timeseries_json  = COALESCE(?, timeseries_json),
+                     geojson          = COALESCE(?, geojson),
+                     source_hash      = ?
+                 WHERE id = ?`,
+                [
+                  JSON.stringify(data.detail),
+                  data.timeseries ? JSON.stringify(data.timeseries) : null,
+                  data.geojson    ? JSON.stringify(data.geojson)    : null,
+                  data.source_hash,
+                  row.id,
+                ],
+              );
+            }
+          } catch {
+            // Non-fatal: synced_at is already set, local data stays as-is
+          }
+        }
         uploaded++;
       } else {
         console.warn(`upload ${row.id}: HTTP ${resp.status}`);