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, 2 insertions, 3 deletions

diff --git a/src/routes/players.rs b/src/routes/players.rs
index 5c90efb..7cfb722 100644
--- a/src/routes/players.rs
+++ b/src/routes/players.rs
@@ -75,14 +75,13 @@ async fn manage_players(
 }
 
 fn read_json_list(path: &std::path::Path) -> Vec<String> {
-    if let Ok(contents) = std::fs::read_to_string(path) {
-        if let Ok(entries) = serde_json::from_str::<Vec<serde_json::Value>>(&contents) {
+    if let Ok(contents) = std::fs::read_to_string(path)
+        && let Ok(entries) = serde_json::from_str::<Vec<serde_json::Value>>(&contents) {
             return entries
                 .iter()
                 .filter_map(|e| e["name"].as_str().map(String::from))
                 .collect();
         }
-    }
     vec![]
 }