CI: Default THROWS_WEB_SMOKE_GATE=1 in ci-fast after #2093 green

[PurHur]

Problem

examples-web-smoke.sh already has a 007-ThrowsWeb slice (--throws-only, THROWS_WEB_SMOKE_GATE) tracked in #2093, but script/ci-defaults.env keeps THROWS_WEB_SMOKE_GATE=0. 005 and 006 VM smokes default-on (#1887, #2009).

Throw/catch presenter regressions stay invisible in ./script/ci-fast.sh until full ci-local.sh.

Scope

1. Wire Testing: THROWSWEB_WEB_SMOKE_GATE + examples-web-smoke 007 slice #2093 completely (Make examples-throws-smoke if still missing; align gate name THROWS_WEB_SMOKE_GATE vs issue title THROWSWEB_WEB_SMOKE_GATE)
2. Flip THROWS_WEB_SMOKE_GATE default to 1 in script/ci-defaults.env
3. Hook in script/ci-fast.sh / ci-common.sh (mirror CI: Default SESSIONS_WEB_SMOKE_GATE=1 in ci-fast after #1887 green #1894)
4. Update examples/007-ThrowsWeb/README.md, ROOT_README_007_SYNC_GATE stale phrases (#2094)
5. Opt-out: THROWS_WEB_SMOKE_GATE=0 for doc-only iteration

Acceptance criteria

./script/ci-fast.sh
docker run --rm -v "$(pwd):/compiler" -w /compiler php-compiler:22.04-dev ./script/ci-fast.sh

• 007 curls run without extra env
• test/unit/CiScriptsTest.php asserts default 1
• Close Testing: THROWSWEB_WEB_SMOKE_GATE + examples-web-smoke 007 slice #2093 when green

Depends on

• Testing: THROWSWEB_WEB_SMOKE_GATE + examples-web-smoke 007 slice #2093 — script/Make/doctor wiring complete
• Examples: 007-ThrowsWeb — throw/catch presenter app (post-#195/#57) #2076 ✅ — tree on master

Links

• Testing: THROWSWEB_WEB_SMOKE_GATE + examples-web-smoke 007 slice #2093 · DevEx: make examples-sessions-smoke — VM curl ladder for 005-SessionsWeb (#1887) #1914 (005 make target pattern) · 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 ROADMAP

[PurHur]

Backlog de-dupe (batch 136): Canonical VM smoke gate for 007 — env THROWS_WEB_SMOKE_GATE (not THROWSWEB_WEB_SMOKE_GATE). #2093 narrowed to #2200 uncaught polish; close #2093 when #2200 lands.