fix: publish the ESM build of @metamask/mobile-wallet-protocol-core

[imaksp]

Description

• FIXED:
  • packages/core builds both CJS and ESM (tsup src/index.ts --format cjs,esm --dts --splitting) but its manifest declares only main + types, so the published dist/index.mjs and dist/index.d.mts are unreachable and every bundler resolves the CommonJS build. This adds module + exports.

dapp-client and wallet-client — same repo, same build script — already declare both fields. core is the only package without them, so this copies their block verbatim.

Why it matters

Resolved as CJS, await import('@metamask/mobile-wallet-protocol-core') gives esbuild-based bundlers a namespace whose named members are undefined. @metamask/connect-multichain does exactly that in #createDappClient(), so mwpCore.SessionStore.create(kvstore) throws undefined is not an object in any browser build of MetaMask Connect — reproduced on Angular 22 / esbuild, where connecting via the MWP QR flow fails outright. We currently ship this change as a pnpm patch.

Issue

Reported downstream as MetaMask/connect-monorepo#342, which covers two bugs of the same kind — this change fixes the mwpCore.SessionStore half of it.

Checklist

• Tests are included if applicable — manifest-only change, no test surface
• Any added code is fully documented

🤖 Generated with Claude Code

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Note

Low Risk
Manifest-only change with no runtime code edits; aligns core with sibling packages and fixes incorrect module resolution for ESM consumers.

Overview
Fixes @metamask/mobile-wallet-protocol-core always resolving to CommonJS even though tsup already emits dist/index.mjs and dist/index.d.mts.

Adds module and a conditional exports map (ESM import → .mjs / .d.mts, CJS require → .js / .d.ts), matching the other packages in this repo. The changelog records the fix under Unreleased → Fixed.

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