repro: KiCad exports omit hierarchical child schematic files - #5218

Motivation

Multi-sheet tscircuit designs export a KiCad root schematic that correctly names and references every child sheet, but the CLI writes only that root .kicad_sch file. The referenced child schematic files are missing from both the KiCad ZIP and the generated project directory.

KiCad therefore shows the expected sheet names in the hierarchy panel, while opening a child sheet produces a blank, unsaved page because its Sheetfile cannot be found. This makes an existing schematic look empty and prevents users from reviewing or editing the exported sheets.

Issue

Reproduction

The fixture declares power and control schematic sheets and assigns one component to each. The CLI integration tests cover both affected paths:

• tsci export index.tsx -f kicad_zip
• tsci build index.tsx --kicad-project

In both outputs, the root schematic references power.kicad_sch and control.kicad_sch, but neither child file is written. The converter already exposes the complete hierarchy through getOutputFiles(); the CLI paths currently use only getOutputString(), which returns the root file.