Docs: Root README north-star drift guard (post-#764 closed claims)

[PurHur]

Problem

#764 ✅ closed — examples/README.md and examples/003-MiniWebApp/README.md document native execute as green, but root README.md still claims partial/blocked execute in multiple places:

Location	Stale claim
§ What works today	003 AOT execute 🚧 partial — home ✅
Quick start L68	native execute blocked #764
Shipped examples table (if present)	may lag examples/README.md

#1822 guards examples/README.md only. Root README drift recurred after #764 close and will recur after #1760 gate flips unless automated.

Goal

1. Add script/check-root-readme-sync.php (or extend an existing checker) that fails on known-stale phrases in README.md:
   • blocked #764, empty stdout until, execute 🚧, native execute blocked
2. Allow #764 only in closed/historical context (same policy as Docs: examples/README drift guard — assert no stale #764 blocked wording #1822 / CapabilitySyntaxTest)
3. Wire into ci-fast.sh via ROOT_README_SYNC_GATE (default 0 until Docs: Rewrite README feature list to match current compiler (2026) #48 / Docs: Sync North Star 1 status — README, #1044, development-status.md (#764 closed) #1525 land; flip to 1 in same PR as doc fix)

Scope

• Checker script + test/unit/RootReadmeSyncTest.php
• script/ci-common.sh hook (mirror CI: Wave 3 roadmap drift guard (docs/roadmap-wave3.md vs #1380) #1802 wave3 pattern)
• docs/local-ci-matrix.md row for the gate
• Fix README in Docs: Rewrite README feature list to match current compiler (2026) #48 / Docs: Sync North Star 1 status — README, #1044, development-status.md (#764 closed) #1525 PR (not required to close this issue first)

Acceptance criteria

php script/check-root-readme-sync.php   # passes after #48/#1525
ROOT_README_SYNC_GATE=1 ./script/ci-fast.sh
docker run --rm -v "$(pwd):/compiler" -w /compiler php-compiler:22.04-dev ./script/ci-fast.sh

Fails with actionable line numbers when stale north-star wording returns.

Dependencies

• Docs: Rewrite README feature list to match current compiler (2026) #48, Docs: Sync North Star 1 status — README, #1044, development-status.md (#764 closed) #1525 — README content fix (blocker for default-on gate)
• Docs: examples/README drift guard — assert no stale #764 blocked wording #1822 — examples/README sibling guard (land together or immediately after)

Non-goals

• GitHub Actions workflow (Disable github actions for now #394 ✅ closed)
• Editing docs/capabilities*.md (Docs: Sync capability-syntax + capability-matrix rows post-#764 (execute ✅) #1767 ✅)

Links

• ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 Phase 4 polish
• North Star 1 🌐 North Star 1: Web-capable PHP application (living tracker) #1044
• Examples guard Docs: examples/README drift guard — assert no stale #764 blocked wording #1822