perf(webpack-cli): cache schema arguments and use map lookups for options

.changeset/fast-pumas-cache.md

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+"webpack-cli": patch
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+Cache CLI argument metadata built from the webpack/dev-server schema and apply CLI options using the cached name-keyed map directly, avoiding a redundant schema walk and the rebuild of a large options array and lookup map on every run. Default-config discovery now reads each candidate directory once instead of probing every `<name><ext>` combination with a separate `fs.access` call (up to ~100 sequential syscalls when no config file exists). Colors are also created lazily, so commands that don't need webpack (such as `version` and `info`) no longer load it. The cached argument metadata (~1MB per schema) is held via `WeakRef` so the garbage collector can reclaim it once command setup is done, which matters for long-running `serve`/`watch`. The `serve` command no longer retains the full option arrays (~900KB) in its context for the whole session, deriving the lookups it needs from the cached argument metadata instead. Command setup now registers only the options actually present in the arguments instead of all ~850, which roughly halves command-setup time and avoids retaining ~1.4MB of option objects per run (help still lists every option). This reduces per-invocation CPU work, syscalls, and memory usage.