…kg.pr.new

The action now takes a required `packages` input (dir list, trailing /*
globs), packs each directory with `pnpm pack` (resolving workspace:/catalog:
specs; requires pnpm on PATH and a prior `pnpm install`), and pins deps
between batch members to the synthetic commit version via the new optional
RewriteEnv.batchPackages, replacing the round-trip that re-parsed the
pkg.pr.new URLs pkg-pr-new itself injected. A workspace dep missing from the
batch fails the run before anything uploads. The Worker's pkg.pr.new fallback
path is unchanged.

This makes the bridge publish independent of pkg.pr.new (works during its
outages and for commits never published there) and lets the workflow list
packages/cli/cli-npm/*, so the @voidzero-dev/vite-plus-cli-* binaries get
real bridge-served tarballs with integrity instead of a 302 to pkg.pr.new,
which the install.sh bridge migration needs.

Also: warm.mjs now requires --repo <built vite-plus checkout> (one sha per
run), the action source and its tests are typechecked against Node types via
tsconfig.action.json, and vitest is split into worker and action projects
(the action tests spawn pnpm pack on a fixture workspace).

…efaults

- Move the batch off RewriteEnv (per-run caller state, not config): it is now
  an optional arg of rewritePackageJson/buildPreviewTarball, unified with the
  Worker's implicit batch (pinned = batch ?? PREVIEW_PACKAGES). The pkg.pr.new
  fields become optional so the action stops fabricating placeholder values;
  pkgPrNewUrlToVersion returns null without them (Worker still provides them).
- Extract assertValidBatch into localPack.ts, sharing DEPENDENCY_FIELDS with
  the rewrite so the up-front check cannot drift from what gets pinned; the
  error paths (plus empty batch) are now unit-tested.
- Pack one directory ahead while the current package uploads; the
  bridge-visible order (upload -> publish per package, register last) is
  unchanged.
- The packages default lives once in the action code; action.yml documents it
  and warm.mjs omits the input unless --packages overrides. warm.mjs uses
  node:util parseArgs instead of a hand-rolled flag loop.