Add emulator artifact bundles and CI fixtures for pass/fail/crash classification #26

Goal

Make build outputs and tests emulator-aware so runners have a stable artifact bundle and CI can classify pass/fail/crash behavior reliably.

Why

Different emulators require different artifact shapes. Today the build side is close, but not explicit enough for a generic runner layer. We also need deterministic fixtures for crash/pass/timeout behavior before emulator support can be trusted in CI.

Scope

• extend build results to expose emulator-ready artifact bundles, not just one firmware path
• standardize artifact naming for ELF, HEX, BIN, bootloader, partitions, and merged images
• add deterministic pass, fail, timeout, and crash fixtures
• add golden tests for result classification
• ensure supported emulator targets assert the presence of required artifact bundles

Acceptance criteria

• emulator-capable boards expose a machine-readable artifact bundle
• fixtures exist for pass/fail/timeout/crash classification
• CI-safe tests validate classification behavior without hardware
• runner implementations can consume the artifact bundle without board-specific scraping logic

Likely files

• build result/model types
• board-family orchestrators
• emulator test fixtures
• classification tests

Parent: #21