feat: add support for custom user action scripts

Add ability to define custom actions by placing executable scripts in
~/.config/illogical-impulse/actions/

- Script filename becomes the action name (extension stripped)
- Use /script-name in search bar to execute
- Arguments are passed to the script
- Uses FolderListModel for auto-reload when scripts are added/removed
- Follows existing pattern of user-customizable directories (ai/prompts)

dots/.config/quickshell/ii/modules/common/Directories.qml

@@ -44,6 +44,7 @@ Singleton {
     property string wallpaperSwitchScriptPath: FileUtils.trimFileProtocol(`${Directories.scriptPath}/colors/switchwall.sh`)
     property string defaultAiPrompts: Quickshell.shellPath("defaults/ai/prompts")
     property string userAiPrompts: FileUtils.trimFileProtocol(`${Directories.shellConfig}/ai/prompts`)
+    property string userActions: FileUtils.trimFileProtocol(`${Directories.shellConfig}/actions`)
     property string aiChats: FileUtils.trimFileProtocol(`${Directories.state}/user/ai/chats`)
     property string aiTranslationScriptPath: FileUtils.trimFileProtocol(`${Directories.scriptPath}/ai/gemini-translate.sh`)
     property string recordScriptPath: FileUtils.trimFileProtocol(`${Directories.scriptPath}/videos/record.sh`)
@@ -59,6 +60,7 @@ Singleton {
         Quickshell.execDetached(["bash", "-c", `rm -rf '${latexOutput}'; mkdir -p '${latexOutput}'`])
         Quickshell.execDetached(["bash", "-c", `rm -rf '${cliphistDecode}'; mkdir -p '${cliphistDecode}'`])
         Quickshell.execDetached(["mkdir", "-p", `${aiChats}`])
+        Quickshell.execDetached(["mkdir", "-p", `${userActions}`])
         Quickshell.execDetached(["rm", "-rf", `${tempImages}`])
     }
 }