* refactor(anthropic): explore official Claude Agent SDK runtime
* refactor(anthropic): replace handwritten Claude sessions with SDK
* refactor(anthropic): collapse SDK live-session ownership
* refactor(anthropic): simplify SDK ownership and preserve live skills
* fix(anthropic): fence cancelled SDK runs before process startup
* fix(anthropic): harden SDK approvals, lifecycle, and packaging
* refactor(anthropic): own SDK process trees and streamline runtime
* fix(anthropic): repair rebased packaging and legacy test fixtures