Web: FastCGI request loop adapter (nginx / php-fpm compatible)

[PurHur]

Problem

#50 targets CGI/1.1 stdin/stdout. Production stacks use FastCGI (multiplexed, SCRIPT_FILENAME, REQUEST_URI params). bin/serve.php is TCP-only dev server.

Goal

bin/fcgi.php or bin/phpc fcgi that speaks FastCGI RECORD protocol, spawns compiled/VM script per request, populates superglobals via #49.

Implementation plan

1. Parse FastCGI params → putenv + Superglobals::populateFromEnvironment.
2. STDOUT/STDERR streams for response; support Status: header.
3. Integration test: spawn with cgi-fcgi or minimal mock client.
4. Document nginx fastcgi_pass snippet in examples.

Acceptance criteria

• One GET request returns 200 HTML from examples/001-SimpleWeb/example.php
• Works with VM; AOT binary as fastcgi-script when Web: Runtime-populated superglobals for JIT and AOT (per-request $_GET/$_POST) #49 done

Links

• Web: Runtime-populated superglobals for JIT and AOT (per-request $_GET/$_POST) #49 runtime superglobals
• Web: CGI/1.1 request driver (stdin/stdout, env, Status line) #50 CGI driver (share param mapping code)