build: migrate repository tooling to pnpm workspace

[kunchenguid]

What Changed

• Replaced npm lockfiles across the root, benchmark packages, and packages/axi-sdk-js with a shared pnpm-lock.yaml and pnpm-workspace.yaml.
• Updated package metadata, tests, and GitHub Actions workflows to install and run from the pnpm workspace, including CI path filters for shared workspace files.
• Refreshed README and agent development instructions so benchmark and SDK commands use pnpm workspace-aware invocations.

Risk Assessment

✅ Low: The remaining changes are limited to package-manager migration, workspace lockfile consolidation, and CI command/path-filter updates, with the prior material CI coverage gap addressed and no additional substantiated merge-blocking risks found.

Testing

• Summary: Exercised the new pnpm workspace install plus the SDK, browser benchmark, and GitHub benchmark Vitest suites; an SDK test setup issue was fixed and all relevant tests now pass.
• pnpm install --frozen-lockfile
• pnpm --dir packages/axi-sdk-js test
• pnpm --dir bench-browser test
• pnpm --dir bench-github test
• Outcome: ✅ passed across 1 run (1m57s)

Pipeline

Updates from git push no-mistakes

⏭️ **intent** - skipped

Round 1 - passed ✅

✅ **Rebase** - passed

Round 1 - passed ✅

🔧 **Review** - 1 issue found → auto-fixed

Round 1 - found 1 warning

• ⚠️ .github/workflows/axi-sdk-js-ci.yml:28 - This job now installs from the root pnpm-lock.yaml, but the workflow path filters still only include packages/axi-sdk-js/** and the workflow file. A PR that only updates the shared lockfile or root pnpm workspace config for axi-sdk-js dependencies will skip this CI workflow, unlike the previous per-package package-lock.json setup. Add pnpm-lock.yaml, pnpm-workspace.yaml, and the root package.json to the relevant path filters.

Round 2 (auto-fix) - passed ✅

✅ **Test** - passed

Round 1 - passed ✅

• pnpm install --frozen-lockfile
• pnpm --dir packages/axi-sdk-js test
• pnpm --dir bench-browser test
• pnpm --dir bench-github test

🔧 **Document** - 4 issues found → auto-fixed

Round 1 - found 4 warnings

• ⚠️ README.md:100 - The Browser Benchmark development instructions still use npm commands even though this change removes package-lock.json files, adds pnpm-workspace.yaml, and declares pnpm@11.1.1 as the repository package manager. Update this section to install and run the browser benchmark through pnpm/workspace-aware commands.
• ⚠️ README.md:125 - The GitHub Benchmark development instructions still use npm commands even though the repo now uses a pnpm workspace and the bench-github package-lock.json was removed. Update this section to use pnpm for installation and benchmark/report commands.
• ⚠️ AGENTS.md:20 - The agent-facing development command reference still tells agents to run npm install/npm run/npm test in bench-github and bench-browser. Because the change migrates dependency management to a root pnpm workspace, these instructions are stale and should be updated to pnpm commands.
• ⚠️ packages/axi-sdk-js/README.md:83 - The axi-sdk-js development section still says to run npm ci inside packages/axi-sdk-js, but the package-specific package-lock.json was removed and CI now installs from the root pnpm workspace. Update the development instructions to use pnpm install from the workspace and pnpm --dir packages/axi-sdk-js for test/build commands.

Round 2 (auto-fix) - passed ✅

✅ **Lint** - passed

Round 1 - passed ✅

✅ **Push** - passed

Round 1 - passed ✅