Add per-instance mod management with client-side detection

- New mod validation engine (src/mods.rs) with constant-pool class-file
  scanning: detects server-side content (block, tileentity, command,
  worldgen) vs client-only API (gui, renderer, forge/client)
- 7 client-only mods correctly detected (AppleSkin, CraftingTweaks,
  Durability101, EnchantmentDescriptions, InventoryHUD, MouseTweaks,
  TrashSlot); 51 server-capable; 1 unknown
- Routes + templating for mod upload (jar/zip), listing, delete, rescan
- Multipart upload with 500MB limit (bypasses axum's default 2MB)
- Per-instance mod summary card on edit page
- Whitelist toggle checkbox on edit page (persisted, drives ENABLE_WHITELIST)
- Dynamic Java image tag (java8/java17/java21) based on MC version
- Class scan is informational-only; rejection based on metadata side=CLIENT
- has_modpack flag cleanup on mod delete
- Remove hx-boost from <body> (was corrupting multipart uploads)

1 files changed, 3 insertions, 5 deletions

diff --git a/src/routes/backups.rs b/src/routes/backups.rs
index 6f7617e..d68be8d 100644
--- a/src/routes/backups.rs
+++ b/src/routes/backups.rs
@@ -119,14 +119,12 @@ async fn create_backup(
         if let Ok(entries) = std::fs::read_dir(&data_dir) {
             for entry in entries.flatten() {
                 let path = entry.path();
-                if path.is_file() {
-                    if let Some(name) = path.file_name() {
-                        if let Ok(contents) = std::fs::read(&path) {
+                if path.is_file()
+                    && let Some(name) = path.file_name()
+                        && let Ok(contents) = std::fs::read(&path) {
                             let _ = zip.start_file(&*name.to_string_lossy(), options);
                             let _ = std::io::Write::write_all(&mut zip, &contents);
                         }
-                    }
-                }
             }
         }
         let _ = zip.finish();