feat: file dispatch system, file-type icons, multi-instance notepad

- Add extension-based dispatch to driver.storage.filedispatch with typed
  union (variant record THandlerKind = hkMagic/hkExtension)
- Extract file-type icon constants and mapping to core.gfx.fileicons
- Add core.search utility (getFileExtension, fmtFileSize, sortStringArray)
- Generate PUA bitmap icon fonts (32/64/128px) from Font Awesome via
  gen_file_icons.py + compile_icons.sh toolchain
- Integrate file dispatch into file browser (double-click triggers dispatch)
- Register notepad as handler for text file extensions
- Fix init order in app.mgr (filedispatch.init before app inits)
- Refactor notepad from singleton to multi-instance (up to 8 windows)
  using instance array, findStateByWid, and LVGL user_data on msgboxes

src/core/ds/core.ds.hashmap.pas

@@ -119,10 +119,10 @@ begin
     if map^.count > max_load then begin
         NewSize:= map^.Size * 2;
         NewTable:= DPHashItem(kalloc(sizeof(PHashItem) * NewSize));
-        for i:=0 to NewSize-1 do begin
-            NewTable[i]:= nil;
-        end;
         If NewTable <> nil then begin
+            for i:=0 to NewSize-1 do begin
+                NewTable[i]:= nil;
+            end;
             for i:=0 to map^.size-1 do begin
                 item:= map^.table[i];
                 while item <> nil do begin