ext-zealphp: ZealPHP's own ~650-line C extension
- 8 PHP functions: override/restore + superglobals management + coroutine hooks
- 53 PHP built-in function overrides (allowlist-only, no class manipulation)
- Per-coroutine superglobal isolation via OpenSwoole scheduler hooks
- 16 PHPT tests, proven zero-leak with Channel-synchronized interleaving
- PIE-ready: pie install sibidharan/ext-zealphp

Framework:
- App.php auto-detects ext-zealphp > uopz fallback
- superglobals(true) + enableCoroutine(true) now SAFE with ext-zealphp
- composer.json: ext-uopz removed from require
- setup.sh: all 3 paths (Linux/Docker/macOS) install ext-zealphp
- CI: builds ext-zealphp from source in test pipeline

Docs: uopz → ext-zealphp across 20+ pages, PECL → PIE,
5 new mermaid diagrams, lesson build-prep callouts,
syntax highlighting fixes, stale claims removed