feat: replace collision strategy dropdown with inline conflict resolution UI

- Remove the collision strategy dropdown; always default to "rename"
- Add a "Conflicts to resolve" chores list above the package file tree
  showing each collision with editable rename fields (oldname → newname)
- Default rename uses source folder prefix (e.g. gstack-CEO)
- Per-item "skip" button that syncs with file tree checkboxes
- COMPANY.md defaults to skip when importing to an existing company
- Add nameOverrides support to API types and server so user-edited
  renames are passed through to the import

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/shared/src/validators/company-portability.ts

@@ -167,6 +167,7 @@ export const companyPortabilityPreviewSchema = z.object({
   target: portabilityTargetSchema,
   agents: portabilityAgentSelectionSchema.optional(),
   collisionStrategy: portabilityCollisionStrategySchema.optional(),
+  nameOverrides: z.record(z.string().min(1), z.string().min(1)).optional(),
 });
 
 export type CompanyPortabilityPreview = z.infer<typeof companyPortabilityPreviewSchema>;