build: stabilize package boundaries and smoke tests

[rayrayraykk]

Linked Issues

• Related to feat: align TypeScript SDK with AgentScope Python incrementally #49

Description

Background and purpose

This is the first independently reviewable PR extracted from the preserved #48 snapshot. It stabilizes package boundaries and packed-package validation before Python parity features are introduced.

Changes

• Replace internal barrel imports with direct runtime imports and import type where appropriate.
• Add a platform-neutral package smoke script.
• Verify every currently published subpath through ESM and CommonJS after npm pack.
• Reuse the smoke script in CI instead of shell-specific inline commands.
• Normalize pnpm-workspace.yaml to the repository's current Prettier output.

Scope

This PR contains no new public APIs, Python parity data, runtime behavior changes, or Service/Desktop architecture changes.

Review guide

1. Review packages/agentscope/src/**: these edits only replace barrel imports with direct value/type imports.
2. Review scripts/package-smoke.mjs: it packs the package into a temporary directory, installs it, and loads every existing export through ESM and CommonJS.
3. Review the small CI and package-script changes last.

Verification

npx --yes pnpm@9.15.9 install --frozen-lockfile
npx --yes pnpm@9.15.9 format
npx --yes pnpm@9.15.9 run build:agentscope
npx --yes pnpm@9.15.9 run test:package
npx --yes pnpm@9.15.9 run test:agentscope
npx --yes pnpm@9.15.9 run build:desktop

Local verification passed:

• Core ESM/CJS/DTS build.
• Packed-package smoke for 10 ESM and 10 CommonJS exports.
• 126 Core tests.
• Desktop typecheck and build.
• Formatting with no diff.

GitHub Actions passed on Ubuntu, macOS, and Windows.

Dependency

• Base: main
• Depends on: none
• Can be reviewed independently from test(parity): add pinned Python manifest checks #51
• Full snapshot for reference only: rayrayraykk:feat/parity-foundation

Checklist

• This PR is linked to a related issue (see above)
• Code has been formatted with pnpm format
• Related documentation has been updated (not applicable: no user-facing behavior changes)
• All tests are passing (pnpm test and the focused commands above)
• Code is ready for review

[rayrayraykk]

Closing this preparatory PR. I will resubmit the work as small, user-facing parity changes with only the tests required by each feature.