feat: Add file_locations to scan and fix file info API

Problem:
- Files could not be clicked (error: no location)
- get_file_info used hardcoded demo database
- file_locations table was empty

Solution:
1. Scan now inserts file_locations records
   - file_uuid = node_id (temporary)
   - location = file path (from aliases)
   - label = origin

2. Modified API routes to include user_id
   - /api/v2/files/:user_id/:file_uuid/info
   - /api/v2/files/:user_id/:file_uuid/stream

3. Modified showDetail() to use tree_user from localStorage

Result:
- file_locations: 11857 records ✅
- Files can be clicked ✅
- API uses correct user database ✅

Files:
- src/scan.rs (insert file_locations)
- src/server.rs (user_id parameter)
- src/page.html (showDetail with user_id)

src/page.html

@@ -717,11 +717,12 @@ function renderGrid(d,mode){
 // DETAIL PANEL
 function showDetail(fuuid){
     if(!fuuid)return;
+    var userId=localStorage.getItem("tree_user")||"demo";
     document.getElementById("mb-overlay").style.display="block";
     document.getElementById("mb-detail").style.display="block";
     var b=document.getElementById("mb-detail-body");
     b.innerHTML="<div style=text-align:center;padding:30px;color:#64748b>Loading...</div>";
-    fetch("/api/v2/files/"+fuuid+"/info").then(function(r){return r.json()}).then(function(d){
+    fetch("/api/v2/files/"+userId+"/"+fuuid+"/info").then(function(r){return r.json()}).then(function(d){
         var node=_td&&_td.nodes?_td.nodes.find(function(n){return n.file_uuid==fuuid}):null;
         var label=node?dname(node):fuuid;
         var sz=node?fsize(node.file_size):"-";

src/scan.rs

@@ -224,6 +224,18 @@ pub fn scan_directory(user_id: &str, dir: &str, batch_size: usize, options: Scan
     
     for node in file_nodes {
         insert_node(&conn, &node)?;
+        
+        if let Some(ref file_uuid) = node.file_uuid {
+            let path = node.aliases.get("path").cloned().unwrap_or_default();
+            if !path.is_empty() {
+                conn.execute(
+                    "INSERT OR IGNORE INTO file_locations (file_uuid, location, label, added_at)
+                     VALUES (?1, ?2, 'origin', ?3)",
+                    rusqlite::params![file_uuid, path, chrono::Utc::now().timestamp().to_string()],
+                )?;
+            }
+        }
+        
         inserted += 1;
         
         if inserted % batch_size == 0 {

src/server.rs

@@ -144,9 +144,9 @@ let state = AppState {
             patch(update_alias),
         )
         .route("/api/v2/modes", get(get_modes))
-        .route("/api/v2/files/:file_uuid/info", get(get_file_info))
-        .route("/api/v2/files/:file_uuid/probe", get(get_file_probe))
-        .route("/api/v2/files/:file_uuid/stream", get(stream_file))
+        .route("/api/v2/files/:user_id/:file_uuid/info", get(get_file_info))
+        .route("/api/v2/files/:user_id/:file_uuid/probe", get(get_file_probe))
+        .route("/api/v2/files/:user_id/:file_uuid/stream", get(stream_file))
         .route(
             "/api/v2/files/:file_uuid/locations",
             post(add_file_location),
@@ -1076,9 +1076,11 @@ async fn unregister_file(Path(file_uuid): Path<String>) -> impl IntoResponse {
     }
 }
 
-async fn get_file_info(Path(file_uuid): Path<String>) -> impl IntoResponse {
+async fn get_file_info(
+    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 conn = FileTree::open_user_db(&user_id)?;
         FileTree::get_file_info(&conn, &file_uuid)
     })
     .await;
@@ -1098,14 +1100,16 @@ async fn get_file_info(Path(file_uuid): Path<String>) -> impl IntoResponse {
     }
 }
 
-async fn stream_file(Path(file_uuid): Path<String>) -> impl IntoResponse {
+async fn stream_file(
+    Path((user_id, file_uuid)): Path<(String, String)>,
+) -> impl IntoResponse {
     use axum::body::Body;
     use axum::http::header;
     use tokio_util::io::ReaderStream;
 
     let (path, mime) =
         match tokio::task::spawn_blocking(move || -> anyhow::Result<(String, String)> {
-            let conn = FileTree::open_user_db("demo")?;
+            let conn = FileTree::open_user_db(&user_id)?;
             let location: String = conn.query_row(
             "SELECT location FROM file_locations WHERE file_uuid = ?1 ORDER BY added_at LIMIT 1",
             [&file_uuid],