add option to disable keybindings fixing #1251 (#1254)

* add option to disable keybindings

* add tests for disabling keybindings

* Fixed translation keys

* Added env to env configuration list

* Removed useless tests

The tests are already enforced by type declarations

---------

Co-authored-by: Jan Böhmer <mail@jan-boehmer.de>

docs/configuration.md

@@ -129,6 +129,8 @@ bundled with Part-DB. Set `DATABASE_MYSQL_SSL_VERIFY_CERT` if you want to accept
   unique increments for parts within a category hierarchy, ensuring consistency and uniqueness in IPN generation.
 * `IPN_USE_DUPLICATE_DESCRIPTION`: When enabled, the part’s description is used to find existing parts with the same 
   description and to determine the next available IPN by incrementing their numeric suffix for the suggestion list.
+* `KEYBINDINGS_SPECIAL_CHARS_ENABLED`: Set this to 0 to disable the special character keybindings (Alt + key) for inserting special characters. This can be useful if
+  they conflict with your keyboard layout or system shortcuts.
 
 ### E-Mail settings (all env only)
 

docs/usage/keybindings.md

@@ -8,6 +8,21 @@ parent: Usage
 
 This page lists all the keybindings of Part-DB. Currently, there are only the special character keybindings.
 
+## Disabling keybindings
+
+If you want to disable the special character keybindings (for example, because they conflict with your keyboard layout or system shortcuts), you can do so in two ways:
+
+### Via the System Settings UI (recommended)
+
+1. Navigate to **System Settings** (Tools → System Settings)
+2. Go to **Behavior** → **Keybindings**
+3. Uncheck **Enable special character keybindings**
+4. Save the settings
+
+### Via Environment Variable
+
+Alternatively, you can set the environment variable `KEYBINDINGS_SPECIAL_CHARS_ENABLED=0` in your `.env.local` file or your server environment configuration.
+
 ## Special characters
 
 Using the keybindings below (Alt + key) you can insert special characters into the text fields of Part-DB. This works on