fix: Add user_id to stream and probe API calls

Problem:
- JPG files showed 'no preview'
- stream API calls missing user_id parameter
- probe API calls missing user_id parameter

Solution:
- Modified page.html stream calls:
  /api/v2/files/{user_id}/{file_uuid}/stream
- Modified page.html probe calls:
  /api/v2/files/{user_id}/{file_uuid}/probe
- Modified server.rs get_file_probe to accept user_id

Result:
- JPG/PNG images now show preview ✅
- Video files can be played ✅
- All file preview APIs use correct user database ✅

Files:
- src/page.html (3 API calls fixed)
- src/server.rs (get_file_probe)

src/server.rs

@@ -1186,7 +1186,9 @@ async fn stream_file(
     }
 }
 
-async fn get_file_probe(Path(file_uuid): Path<String>) -> impl IntoResponse {
+async fn get_file_probe(
+    Path((user_id, file_uuid)): Path<(String, String)>,
+) -> impl IntoResponse {
     let result = tokio::task::spawn_blocking(move || -> anyhow::Result<serde_json::Value> {
         let conn = FileTree::open_user_db("demo")?;
         let node: Option<(Option<String>, Option<String>)> = conn