fix(gh-aw): Inconsistent use of ID vs name in labels and paths #1625

Bug

The workflow instructions alternate between role-id (registry keys), squad:{id} (labels), and squad:{name} / .squad/agents/{name}/ (paths). Current automation derives labels from member names, not separate IDs. If IDs ever differ from cast names, generated instructions will reference non-existent labels/paths.

Found by: GPT-5.4 code review on PR #1622
Severity: Medium

Fix

Standardize on cast name as the canonical identifier everywhere: registry keys, labels, charter paths, and meet-the-squad references. Remove the role-id concept from the registry template (use the cast name directly as the key).

Part of #1612 epic.