perf(zero-cache): batch serving replica apply work

[Karavil]

what changed

Batches serving-replica apply work in ChangeProcessor, including consecutive same-shape inserts and change-log writes.

benchmark output

medium-wide-batch-pressure, 15s, compared to storer batching:

tx/s: 804.0 -> 941.6
rows/s: 16,079.5 -> 18,832.4
fanout msg/s: 26,125.9 -> 30,654.6
avg VS tx apply: 0.881 ms -> 0.747 ms

validation

pnpm exec vitest --project='*no-pg*' run src/services/replicator/change-processor.test.ts src/types/lite.test.ts
pnpm run check-types
pnpm exec oxlint --config ../../oxlint.config.ts src/services/replicator/change-processor.ts src/types/lite.ts

[Karavil]

Replaced by rocicorp/mono PRs rocicorp#6070 through rocicorp#6078.