fix: store shell path instead of name in defaultShell settings

The defaultShell setting was storing shell.name (e.g., "pwsh") instead
of shell.path (e.g., "C:\Program Files\PowerShell\7\pwsh.exe"). This
caused the backend to fail PATH resolution and fall back to the wrong
shell (Windows PowerShell 5 instead of PowerShell 7).

Changes:
- AppPreferences.tsx: Use shell.path as option value
- ProjectSidebar.tsx: Use shell.path for project default shell
- Display shell.displayName for cleaner UI

Fixes #59

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

Author: gnoviawan

src/renderer/components/ProjectSidebar.tsx

@@ -215,8 +215,8 @@ export function ProjectSidebar({
       const project = projects.find((p) => p.id === projectId)
       const shellSubmenu: ContextMenuSubItem[] = availableShells?.available.map((shell) => ({
         label: shell.displayName,
-        value: shell.name,
-        isSelected: project?.defaultShell === shell.name
+        value: shell.path,
+        isSelected: project?.defaultShell === shell.path
       })) || []
 
       const items: ContextMenuItem[] = [
@@ -237,8 +237,8 @@ export function ProjectSidebar({
           label: 'Set Default Shell',
           icon: <Terminal size={14} />,
           submenu: shellSubmenu,
-          onSubmenuSelect: (shellName: string) => {
-            onUpdateProject(projectId, { defaultShell: shellName })
+          onSubmenuSelect: (shellPath: string) => {
+            onUpdateProject(projectId, { defaultShell: shellPath })
           }
         })
       }

src/renderer/pages/AppPreferences.tsx

@@ -293,8 +293,8 @@ export default function AppPreferences(): React.JSX.Element {
                   >
                     <option value="">System Default</option>
                     {availableShells?.available?.map((shell) => (
-                      <option key={shell.path} value={shell.name}>
-                        {shell.name} ({shell.path})
+                      <option key={shell.path} value={shell.path}>
+                        {shell.displayName}
                       </option>
                     ))}
                   </select>