CI: Default MINIWEBAPP_SERVE_GATE=1 in ci-local.sh (promote gate ladder stage 2)

[PurHur]

Problem

#622 ✅ wired MINIWEBAPP_SERVE_GATE=1 into script/ci-local.sh / ci-fast.sh, but the env defaults to off. #470 ServeTest @group miniwebapp is green on master; contributors running full CI still skip HTTP route regressions unless they export the gate manually (#472 stage 2).

Goal

Promote stage 2 of the MiniWebApp gate ladder so default ./script/ci-local.sh runs MiniWebApp ServeTest when loopback bind is available (same guard as @group serve).

Scope

• Default MINIWEBAPP_SERVE_GATE=1 in script/ci-local.sh (document opt-out MINIWEBAPP_SERVE_GATE=0 for fast iteration)
• Optional: same default in script/ci-fast.sh behind serve bind probe
• Update script/miniwebapp-gates.sh stage-2 detection (env default vs explicit export)
• examples/003-MiniWebApp/README.md + DevEx: MiniWebApp CI gate ladder (lint → serve → AOT → web-smoke) #472 ladder table
• test/unit/CiScriptsTest.php — assert default or documented override

Acceptance criteria

./script/ci-local.sh --filter ServeTest
# Harness (no GHA):
./script/docker-ci-local.sh --filter ServeTest

With loopback available → MiniWebApp ServeTest runs without exporting env. With PHP_COMPILER_SKIP_SERVE_TESTS=1 → skip with clear message (unchanged).

Dependencies

• Testing: ServeTest MiniWebApp routes via phpc serve (skipped until #67) #470 ✅ ServeTest routes
• CI: MINIWEBAPP_SERVE_GATE opt-in for ci-local.sh (ServeTest @group miniwebapp) #622 ✅ ci-local hook
• Reference app: MiniWebApp runtime green (lint 0, VM serve, routes) #539 ✅ VM runtime
• DevEx: MiniWebApp CI gate ladder (lint → serve → AOT → web-smoke) #472 — parent ladder

Links

• test/real/ServeTest.php, ROADMAP 🗺️ ROADMAP: Compile a small PHP web application (living document) #78