Split exports info by compilation phase to avoid whole-map snapshots

[hardfist]

Problem

ExportsInfoData mixes reusable export facts with mutable state from later compilation phases: provided exports, re-export targets, runtime usage, mangling constraints, and inline/rename decisions.

Incremental compilation currently snapshots the entire exports-info map after finish_modules and restores it before the next rebuild. Later passes modify more than usage: side-effects optimization rewrites targets, and some plugins also change provided information. Clearing usage alone cannot replace the snapshot.

Proposed direction

• Keep reusable export facts owned by export analysis; recompute affected modules during incremental builds.
• Separate initial usage requirements (e.g. library exports), per-build usage results, optimization overrides, and inline/rename decisions.
• Provide a combined read-only view and phase-specific write APIs. Preserve late usage updates from plugins such as RSC.
• Remove the whole-map snapshot once later phases no longer mutate reusable facts. Verify incremental output against clean builds, especially when exports, re-export targets, or usage change.

This targets data ownership and deep copies; Arc handle clones are out of scope.

Code references

• ExportInfoData fields
• Checkpoint after finish_modules and whole-map clone
• Target mutation during side-effects optimization