v0.4.0 — ss-evolve --since + --explore

SuperStack v0.4.0 extends /ss-evolve with two new flags — both cross-platform (bash + PowerShell), byte-identical output, fully tested.

Added

• ss-evolve --since <window> (Nd / Nh / YYYY-MM-DD) restricts detection to a recent slice of the ledger; composes with every other flag.
• ss-evolve --explore scaffolds a draft new-skill proposal into .superstack/proposals/<name>/ (Tier 2) — never committed; the /ss-evolve skill authors the body and a human promotes it. Dedups independently of --apply via .superstack/explore-state.

Changed

• Repositioned the README, CLAUDE.md, and the plugin/marketplace description around SuperStack as its own framework — added why-it's-better, a capability comparison, use cases, and benefits; reframed credits as inspiration rather than a "distillation."

Full changelog: https://github.com/Mrshahidali420/superstack/blob/main/CHANGELOG.md