mcp-v0.17.0

Chores

• 1.21.0 [skip ci]
• 0.22.0 [skip ci]
• 1.44.2 [skip ci]

Bug Fixes

• preserve empty toolkit base values
• drop empty perform-action catalog rows
• publish GitHub releases for stable versions only

Features

• add package-scoped AI release notes to all six public packages (#508)
• custom-actions authoring kit — canonical ActionSpec with steps/run tiers (#410)