fix(build): the desktop template was never reaching the bundler

`bundle` already had a "linux" key for the deb `libasound2` depends, and this
branch added a second one. JSON keeps the last of a duplicate key, so
`desktopTemplate` was dropped on the floor: the AppImage shipped the stock
Tauri entry with an empty `Categories=`. Merging the two blocks makes the
template take effect. Verified by building the AppImage and reading the entry
out of the AppDir.

While in there, the template now matches flatpak/wtf.tonho.omniget.desktop --
same Categories, plus the GenericName and Keywords that make the app findable
in a menu search -- and says why those three lines are hardcoded instead of
coming from `bundle.category`.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: YahyaZekry

src-tauri/desktop.template

@@ -1,5 +1,11 @@
 [Desktop Entry]
-Categories=Network;FileTransfer;
+# Categories, GenericName and Keywords are hardcoded rather than derived from
+# `bundle.category`: settings.app_category() maps through a fixed AppCategory
+# table that cannot express a multi-value list like Network;FileTransfer;.
+# Keep these three lines in sync with flatpak/wtf.tonho.omniget.desktop.
+Categories=Network;FileTransfer;Utility;
+GenericName=Download Manager
+Keywords=omniget;download;downloader;video;media;udemy;hotmart;youtube;telegram;
 {{#if comment}}
 Comment={{comment}}
 {{/if}}

src-tauri/tauri.conf.json

@@ -62,14 +62,6 @@
       "../browser-extension/chrome/": "browser-extension/chrome/",
       "../browser-extension/firefox/": "browser-extension/firefox/"
     },
-    "linux": {
-      "deb": {
-        "desktopTemplate": "./desktop.template"
-      },
-      "rpm": {
-        "desktopTemplate": "./desktop.template"
-      }
-    },
     "icon": [
       "icons/32x32.png",
       "icons/128x128.png",
@@ -85,7 +77,11 @@
       "deb": {
         "depends": [
           "libasound2"
-        ]
+        ],
+        "desktopTemplate": "./desktop.template"
+      },
+      "rpm": {
+        "desktopTemplate": "./desktop.template"
       }
     }
   }