v0.10.0 — design-md skill + Python 3.9 fix

Minor release. Adds a sixth seed skill and unbreaks brew install for every macOS user on the system Python.

Highlights

• design-md seed skill. A new portable skill that points coding agents at a root DESIGN.md (Google Stitch format) as the visual-system source of truth — colors, typography, spacing, components, rationale. Loads only when DESIGN.md exists at the project root; default behavior is read-only on the contract file. Brings seed skill count from 5 to 6.
• Python 3.9 crash on first run is fixed. Every brew user on macOS-default Python 3.9 was hitting TypeError: unsupported operand type(s) for |: 'type' and 'type' immediately after brew install agentic-stack because harness_manager/ used PEP 604 union syntax (Path | str) that requires Python 3.10+ at runtime. Added from __future__ import annotations to the eight affected files so all annotations are stored as strings and never evaluated at import time. Works on Python 3.7+, which covers every macOS-shipped Python in the wild.

Migration

brew upgrade agentic-stack is enough — no on-disk schema changes. Users on Python 3.9 who hit the crash on v0.9.x: upgrading clears it.

Credits

• PR #21 by @danielfoch (design-md skill), with cross-model review fixes applied as a follow-up commit.
• Issue #27 by @WhoLsJohnGalt — clean repro of the macOS Python 3.9 crash including a working sed-based workaround.
• Codex CLI used for independent second-opinion reviews on both changes.

See CHANGELOG.md for the full list.

Full Changelog: v0.9.1...v0.10.0