Reproduce build succeeding with DRC errors

[ShiboSoftwareDev]

Problem

tsci build writes Circuit JSON containing DRC errors, prints Build completed with errors, and still exits with status 0. A fabrication or CI script therefore cannot distinguish a clean build from a board with reported errors.

Reproduction

The focused CLI test builds a real board with a resistor outside the board boundary. It verifies that the generated Circuit JSON contains the corresponding pcb_component_outside_board_error and records the current contradiction:

• the default command prints Build completed with errors
• the default command exits 0
• --ignore-errors also exits 0

The reproduction changes no CLI implementation.

Expected behavior

The default command should exit nonzero when unignored DRC errors are present. --ignore-errors should remain the explicit opt-in for a successful exit.

Verification

• bun test tests/cli/build/build-with-drc-error.test.ts
• bun run format:check

The fix will be proposed as a separate PR stacked on this branch.

[github-actions]

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