[flitzrrr]

• Fixes docs: Antigravity is instruction-only in README and the portability doc, but INSTALL.md documents a plugin install with commands #1064: INSTALL described native plugin commands while README and the portability table called Antigravity instruction-only.
• Align all three documents and the four translated README host lists with Google's plugin layout and skill slash commands: root plugin.json plus skills/, with AGENTS.md as the instruction-only fallback.
• Remove the stale migration deadline and distinguish native plugins from Gemini extension conversion. No ruleset or runtime changes.
• Validation: uv run --no-project --with pandas npm test passed (127 root + 28 Pi tests); rule-copy and version checks passed; git diff --check passed.
• [UNVERIFIED] Live installation and invocation with agy; this limitation is explicit in INSTALL and the portability table.

[m2nwo079]

Thanks for taking this on, @flitzrrr — the direction here matches what I was hoping for.

For context, I opened #1064 after tracing the inconsistency across INSTALL.md, the README host lists and the portability table, and I offered there to send the one-commit docs PR once a maintainer confirmed which side was stale. This landed first, which is fine by me, but could the merge carry a co-author trailer so the credit is shared?

Co-authored-by: m2nwo079 241894548+m2nwo079@users.noreply.github.com

Same arrangement as #1066. @DietrichGebert — if this is squash-merged, adding that line to the commit message would be enough.

Happy to review the diff against what #1064 describes if that's useful.