feat: mdbid

[brunozoric]

Summary

• Add mdbid utility to the common slice — generates MongoDB-compatible ObjectId hex strings via bson-objectid
• Exported from @webiny/stdlib as a standalone function, no DI setup required
• Adds bson-objectid as a production dependency

Usage

import { mdbid } from "@webiny/stdlib";

const id = mdbid(); // "507f1f77bcf86cd799439011"

Files changed

• src/common/utils/mdbid/mdbid.ts — implementation with CJS interop cast for tsgo
• src/common/utils/mdbid/index.ts — barrel export
• src/common/utils/mdbid/README.md — usage docs
• src/common/index.ts — re-export mdbid
• src/common/utils/README.md — added to utils table
• README.md — added to root feature table
• tests/mdbid.test.ts — 5 tests (format, uniqueness, type, length, hex casing)
• package.json / yarn.lock — bson-objectid@^2.0.4
• .changeset/khaki-lies-see.md — patch changeset

Test plan

• 378 tests passing (373 baseline + 5 new)
• Full pre-commit chain clean (yarn && yarn adio && yarn format:fix && yarn lint:fix && yarn typecheck && yarn build && yarn test:coverage)
• No regressions in existing tests