VSIX includes unneeded files (screenshots, AGENTS.md, skills/, .claude/, test-results, zip, duplicate README) #306

Problem

vsce ls shows the packaged VSIX contains files not needed at runtime or by the Marketplace listing, because .vscodeignore doesn't exclude them:

• assets/screen-*.png (14 screenshots, ~2.6 MB total; not referenced by README.extension.md, which is the README shipped in the VSIX)
• assets/icon.svg (only assets/icon.png is referenced by package.json)
• README.extension.md (duplicate of the swapped-in README.md)
• AGENTS.md, SUPPORT.md
• skills/** and .claude/** (agent tooling, dev-only)
• test-results/** (Playwright output)
• stray *.zip build artifacts

Fix

Extend .vscodeignore to exclude these, keeping dist/, assets/icon.png, README.md, CHANGELOG.md, LICENSE, NOTICE, package.json.