chore: regenerate protobuf protocol with protobufjs-cli 2

[claude]

Requested by Łukasz Komoszyński · Slack thread

This regenerates the committed static protobuf module — libs/schema/src/lib/protocol/index.js and index.d.ts — from contracts.proto using protobufjs-cli 2 (the version #163 bumped to). The goal is to keep the checked-in generated output in sync with the current codegen so it matches what nx run schema:proto-update produces on the new toolchain.

Stacked on #163 — the base of this PR is the chore/npm-dependencies-bump branch, not main.

Notes on the diff:

• The runtime index.js change is purely stylistic: identical enums, field numbers, and methods — no behavioral change.
• The index.d.ts reflects pbts 2's new type-emission style ($Properties / $Shape / $unknowns), while the I* interfaces are retained.
• Files were formatted with the repo's prettier config to match the previously committed output.
• The entire libs/schema/src/lib/protocol/ folder is flagged linguist-generated in .gitattributes (via the glob libs/schema/src/lib/protocol/** linguist-generated=true) so GitHub collapses these diffs and excludes them from language stats. Every tracked file in the folder is non-authored: index.js / index.d.ts are generated by pbjs/pbts (nx run schema:proto-update), and contracts.proto is downloaded from the upstream repo via nx run schema:proto-download (https://raw.githubusercontent.com/leancodepl/contractsgenerator/main/contracts.proto) — none of them are hand-edited here.
• nx run schema:build and nx run-many -t lint build test all pass on Node 24 (31 tests / 23 snapshots across 10 projects).

Keeping as draft.