_selected_board raises AttributeError on a non-mapping eos.yaml (or non-mapping system:) after a successful build #192

What

ebuild/cli/commands.py _selected_board() (lines 504-519) hardcodes Path("eos.yaml"), does yaml.safe_load(...) or {}, then (data.get("system") or {}).get("board"). If the top level of eos.yaml is a list, .get raises AttributeError; if system: is a string, .get("board") raises AttributeError.

Where

The crash happens in _build_summary, i.e. after the image has already linked — a malformed project file turns a successful build into a traceback at the summary step.

Why it matters

Only the eos.yaml copy was missing the guard: _board_config (lines 619-633) already rejects non-mappings (return data if isinstance(data, dict) else None).

Proposed approach

Share one YAML-mapping reader: missing/unreadable/malformed/non-mapping -> None; _selected_board goes through it (plus a system-is-dict guard) and falls back to "generic"; _board_config delegates to the same reader. Behaviour for valid files is unchanged.

Note

PR #191 already implements this fix (shared _read_yaml_mapping, tests for top-level list / system: as string / unclosed YAML). This issue exists so the PR body can link a real closing issue — it previously cited the Fixes #<issue-number> placeholder, which is why the Linked Issue policy check fails.