feat: migrate build to tsup and use near-api-js directly

[mikedotexe]

⚠️ Depends on upstream near-api-js PRs — do not merge until all three land.

near-api-js is currently resolved from github:mikedotexe/near-api-js#pr/tsup-build.
Once the PRs below are merged and a new version is published, this will be
updated to a normal version range.

Upstream dependency chain (must merge in order)

1. near/near-api-js#1894 — Inline borsh serializer, make is-my-json-valid optional
2. near/near-api-js#1895 — Add standalone crypto utils and plain transaction builder (depends on #1894)
3. near/near-api-js#1896 — Switch build from tsc to tsup: ESM + CJS + IIFE output (depends on #1895)

Summary

• Replace @near-js/* scoped packages with near-api-js — all wallet integrations now import from near-api-js directly instead of @near-js/crypto, @near-js/transactions, etc.
• Switch build from tsc to tsup — produces ESM, CJS, and IIFE output with proper exports map
• Remove unnecessary dependencies — drops @meteorwallet/sdk (+ its patch-package hack), @here-wallet/core, @peersyst/near-mobile-signer, @noble/hashes, qr-code-styling, vite-plugin-node-polyfills
• Use crypto utils from near-api-js — signHash, sha256, privateKeyFromRandom, etc. replace direct @noble/hashes usage
• Use plain transaction builders — mapTransaction and mapAction from near-api-js replace hand-rolled conversion code
• Replace qr-code-styling with qrcode-generator — lighter QR code generation

Test plan

• yarn install resolves cleanly (once upstream PRs land)
• yarn build produces dist/ with ESM, CJS, and IIFE bundles
• yarn build:wallets builds all wallet modules without errors
• Wallet integrations work end-to-end (hotwallet, meteor, mnw, near-mobile, nightly, okx, wallet-connect)

🤖 Generated with Claude Code

[mikedotexe]

quite dramatic reduction. big small if true

[frol]

Just for the reference: #73 (comment)