Build the adas-subagent mental model

Common skill stub — the procedure lives in .claude/commands/architect/_common/understand.md. Execute that file's steps with this variant binding:

• VARIANT = adas-subagent
• VARIANT_DIR = .claude/commands/architect/adas-subagent/
• CONFIG = <VARIANT_DIR>/config.yaml § understand:

Variant-specific values (archive path, exp.yaml requirements, archive-preview format, Layer-1 emphasis, bootstrap hint) come from the config — do not duplicate them here.