v4.0 — Postal mail infrastructure, not package warehouse

SKILL.md v3.0.0: spell out signup flow for agents

Bump skill version to 2.0.1 after ClawHub publish

Rewrite skill v2.0 to reflect live platform direction

Bump version to 1.0.5 for ClawHub publish

Update skill description to emphasize mail and document handling

Update rate limit to 30/min and fix repository URL

Initial skill release v1.0.0