SMOODEV-tsdown: migrate logger from tsup to tsdown

[brentrager]

Summary

Drop-in build tooling migration: `tsup` → `tsdown` (oxc-based, faster, actively maintained).

• `tsup.config.ts` → `tsdown.config.ts` (defineConfig import swap)
• Browser build's `esbuild-plugin-alias` shim — which replaces `rotating-file-stream` with a no-op stub — moves to `@rollup/plugin-alias` (rolldown-compatible); `noExternal` becomes `deps.alwaysBundle`
• `src/decycle.cjs` (side-effect CJS that patches global JSON) is marked `external` so rolldown leaves it alone — it's copied to `dist/` as-is post-build, same as before
• `fixedExtension` set explicitly on the browser config so its output matches the core build's extension scheme
• `package.json`: `tsup` → `tsdown` devDep, `esbuild-plugin-alias` swapped for `@rollup/plugin-alias`, `unrun` added; `bin.smooai-log-viewer` updated from `.js` to `.cjs`
• Output extensions shift from `.js`/`.mjs`/`.d.ts` to `.cjs`/`.mjs`/`.d.cts`/`.d.mts` (tsdown defaults). The `exports` map is updated; subpath imports continue to resolve transparently.

Test plan

• `pnpm install` clean
• `pnpm exec tsdown` clean (core + browser + CLI)
• `pnpm exec tsc --noEmit --skipLibCheck` passes
• vitest TS tests pass (55 tests)
• CI green

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: d5ec943

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@smooai/logger	Patch

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