v0.5.6 — Chat requests, Context Tree read skill, release hardening

Highlights

• Chat requests now have explicit open-question resolution, chat descriptions paired with topics, and Needs attention keeps open requests pinned.
• Agents now operate on the chat-send-only contract and include the new first-tree-read skill for scoped Context Tree reads.
• Onboarding and Context Tree setup recover better when admins skipped connecting code, with clearer invitee and team copy.

Notable fixes

• Require explicit production server secrets and remove the retired Feishu/Kael adapter subsystem.
• Lower the published Node engine floor to >=22.13.0 to match resolver-enforced dependencies.
• Degrade GitMirrorAuthError as a source-repo checkout condition, restore composer footer toolbar clicks, and guard prompt edits from pasted assembled briefings.