Problem

tsdown.config.ts duplicates package export maps, output roots, declaration flags, and tsdown defaults across package build graphs. The manual maps repeat 104 package entrypoints already owned by package exports, increasing drift risk and config size.

Desired outcome

• Derive ordinary package entries from each package's published export map.
• Centralize declaration generation and output-root defaults in the package config factory.
• Keep explicit entries only for packages whose source layout or emitted names differ from their exports.
• Remove redundant clean, ESM format, and Node platform settings already supplied by tsdown 0.22.1 or the build wrapper.

Evidence required

• Existing focused tsdown config/build tests.
• Root test typecheck.
• Full build and runtime sidecar-loader check.
• Every derived package import and types target exists after build.

No user-visible behavior change. Internal build configuration only.