Fix hair/vendor/loot bugs, revamp spellbook with tabs and icons, clean up action bar, add talent placeholder

- Fix white hair: always override M2 type-6 texture with DBC hair texture when available
- Fix vendor sell: add sellPrice to ItemDef/ItemTemplateRow, use directly instead of empty cache
- Fix empty loot: skip loot window when corpse has no items and no gold
- Revamp spellbook (P key): tabbed UI (General/Active/Passive), spell icons from SpellIcon.dbc, rank text
- Clean up action bar: only auto-populate Attack and Hearthstone, rest assigned via spellbook
- Add talent placeholder (N key): 3-tab window with level/talent point display
- Fix ffplay cleanup: non-blocking waitpid with SIGKILL fallback to prevent orphaned audio processes
- Fix pre-existing getQualityColor visibility for loot window rendering

include/platform/process.hpp

@@ -122,7 +122,18 @@ inline void killProcess(ProcessHandle& handle) {
     kill(-handle, SIGTERM);  // kill process group
     kill(handle, SIGTERM);
     int status = 0;
-    waitpid(handle, &status, 0);
+    // Non-blocking wait with SIGKILL fallback after ~200ms
+    for (int i = 0; i < 20; ++i) {
+        pid_t ret = waitpid(handle, &status, WNOHANG);
+        if (ret != 0) break;  // exited or error
+        usleep(10000);         // 10ms
+    }
+    // If still alive, force kill
+    if (waitpid(handle, &status, WNOHANG) == 0) {
+        kill(-handle, SIGKILL);
+        kill(handle, SIGKILL);
+        waitpid(handle, &status, 0);
+    }
 #endif
 
     handle = INVALID_PROCESS;