feat(scenarios): add meter-value-zero scenario

[YANGCHUNHONG3000]

Closes #108

Adds the meter-value-zero negative-control scenario using CS-SYNTHETIC-021. The all-zero cumulative meter trace is expected to report no failures, guarding against regressions in METER_VALUE_ANOMALY.

Validation:

• ocpp-debugkit scenario run meter-value-zero: 0 failures, PASS
• lint, package typecheck, package build, and changed-file Prettier checks
• unit suite: 549 tests passed; scripts/update-current-state.test.ts has a pre-existing Windows/Vitest import failure
• packed-tarball consumer verification: 20 scenarios exported and installed CLI passes meter-value-zero

[sepehr-safari]

This is right, and it is the first negative control in the corpus. I ran the trace
through the engine and it reports nothing, which is exactly what the scenario is
for: it pins down that a flat zero register is not a fault, so a future change to
METER_VALUE_ANOMALY cannot start reporting it without a named test failure.
format:check, lint, typecheck and build pass, the suite is at 558, and the
external fixture test is at 56.

One small thing, and it was my fault rather than yours. The corpus numbers the
idTag and transactionId to match the station ID, so CS-SYNTHETIC-021 wants
SYNTHETIC-TAG-021 and 100021. The issue still said SYNTHETIC-TAG-017 and
100017, left over from when the scenario was going to be station 017 before
that number turned out to be taken. You followed the issue exactly. I have pushed
the rename to your branch and corrected the issue text so the next reader does not
inherit it.

Merging now. That takes the corpus to 20 and clears the 20+ target for v1.0, and it
is your third scenario.