chore: migrate from Yarn Classic to pnpm

[akudev]

Replace Yarn 1.x with pnpm 10 as the workspace package manager.

• Add pnpm-workspace.yaml and .npmrc (frozen-lockfile, save-exact, registry pin, shamefully-hoist)
• Add packageManager field for Corepack support
• Update CI workflows with pnpm/action-setup and dependency caching
• Convert workspace cross-reference from link: to workspace: protocol
• Drop lockfile-lint (pnpm lockfile not vulnerable to URL injection; .npmrc registry pin provides equivalent protection)
• Replace npm-run-all in root ci script with plain && chain (npm-run-all2 v5+ delegates to pnpm which chokes on the commitizen config block in package.json)
• Add pnpmDedupe to Renovate postUpdateOptions
• Update documentation

[akudev]

pnpm 12 adaptations:

• packageManager: pnpm@12.4.1 (not 10.x)
• .npmrc: now only has registry= (auth/registry only, per pnpm 12 convention)
• pnpm-workspace.yaml: now carries frozenLockfile, saveExact, minimumReleaseAge, and allowBuilds (pnpm 12 moved settings out of .npmrc)
• allowBuilds: new pnpm 12 feature — explicit approval for packages with build scripts (@parcel/watcher, ui5-tooling-transpile, unrs-resolver)
• No shamefully-hoist: strict node_modules — the proper pnpm benefit

Phantom dependencies fixed (surfaced by strict mode):

• test-packages/typed-json-model: added @eslint/js
• packages/ts-interface-generator: added @eslint/js, @eslint/eslintrc

Pre-existing lint fix (not from migration):

• packages/ts-interface-generator/src/interfaceGenerationHelper.ts: added { cause: e } to two throw new Error() calls to satisfy the preserve-caught-error ESLint rule

[codeworrior]

@petermuessig added a ❤️ to "No shamefully-hoist: strict node_modules — the proper pnpm benefit"...

[akudev]

Added a stricter trust policy - with exceptions as three libs don't reliably publish with provenance.

[codeworrior]

LGTM, independent from the npm vs pnpm question.

[petermuessig]

❤️ it!