feat: add Claude plugin icon and clearer description (0.1.0-canary.2)

[bntvllnt]

Summary

• Adds a repository-owned icon, assets/claude-icon.svg: a square 256px SVG showing an isometric layered stack with a V. The generator copies it into the Claude package as .claude-plugin/icon.svg, as the directory submission check asks.
• Replaces the plugin description (shared by all hosts) and the Claude marketplace description with: "Evidence-led engineering workflows to plan, build, review, and ship software, with shared thinking, orchestration, and collaboration principles."
• Bumps to 0.1.0-canary.2, because Claude Code caches plugins by version. Updates the CHANGELOG and adds assets/claude-icon.svg to the README file table.

Verification

• 37 tests OK. A new assertion checks that the icon ships only in the Claude package.
• sync.py --check: 413 files, no drift. git diff --check clean.
• claude plugin validate passes for the catalog and plugin.
• Rendered the icon in headless Chromium at 256, 128, 64 and 32px on light and dark backgrounds.

https://claude.ai/code/session_01QibzbuYP9NMPNKJdURfxfE