chore: rename package to @nestm/standard-schema

[kauandotnet]

Summary

• rename the npm package from @nestm/nestjs-standard-schema to @nestm/standard-schema
• update the runtime DTO brand, documentation imports, package metadata, security links, and repository URLs
• rename the Changesets prerelease identity while preserving the alpha.0 → alpha.1 flow
• update release PR titles, npm lookups, git tags, and Trusted Publishing instructions

Verification

• pnpm install --frozen-lockfile
• pnpm changeset status
• pnpm run check
• pnpm run test (16 unit + 5 E2E)
• pnpm run verify:pack
• pnpm dlx @arethetypeswrong/cli --pack . --profile esm-only
• actionlint
• pnpm audit --audit-level high --prod
• npm pack --dry-run --json
• isolated Changesets simulation produced @nestm/standard-schema@0.1.0-alpha.1

Release coordination

This supersedes the generated old-name release PR. After this rename reaches main, the release workflow should generate a fresh @nestm/standard-schema release PR.