Fail builds with unignored circuit errors

[ShiboSoftwareDev]

Stack

Review and merge the reproduction first: #4389

This branch is based directly on the reproduction branch, so the PR diff contains only the behavior change and corrected expectations.

Fix

• exit with status 1 when Circuit JSON contains unignored errors
• retain status 1 for fatal generation failures
• retain status 0 when --ignore-errors explicitly suppresses the errors
• retain category-specific ignore behavior: a build only succeeds when every remaining error category is ignored
• report whether the nonzero exit came from a fatal generation failure or unignored circuit errors

Observable result

Command	Reproduction	Fix
tsci build with DRC errors	0	1
tsci build --ignore-errors	0	0

Verification

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

[github-actions]

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