fix: harden auto-skill and optimize assets

[Toolsai]

Summary

• Remove the automatic global IDE/agent rules bootstrap and add explicit write-safety boundaries.
• Repair the experience index so it is valid JSON and points to the Remotion experience entries.
• Replace the large PNG README assets with WebP, and add MIT licensing for Prompt Case.

Validation

• python3 -m json.tool experience/_index.json
• python3 -m json.tool knowledge-base/_index.json
• python3 /Users/mattchan/.agents/skills/skill-creator/scripts/quick_validate.py .
• Verified README asset links and experience index counts.

Notes

• No .github/workflows CI configuration exists in the current main branch, so GitHub may report no automated checks for this PR.
• The PR is opened as a draft until the diff and validation are reviewed.