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, 14 insertions, 0 deletions

diff --git a/src/models/mod.rs b/src/models/mod.rs
index 0b083ff..5cca3ff 100644
--- a/src/models/mod.rs
+++ b/src/models/mod.rs
@@ -9,6 +9,19 @@ pub struct Account {
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[allow(dead_code)]
+pub struct Mod {
+    pub id: i64,
+    pub instance_id: i64,
+    pub filename: String,
+    pub display_name: Option<String>,
+    pub side: String,
+    pub accepted: bool,
+    pub rejection_reason: Option<String>,
+    pub created_at: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Instance {
     pub id: i64,
     pub name: String,
@@ -23,6 +36,7 @@ pub struct Instance {
     pub gamemode: i32,
     pub max_players: i32,
     pub pvp: bool,
+    pub whitelist_enabled: bool,
     pub motd: String,
     pub rcon_password: String,
     pub is_active: bool,