chore: improve incremental typecheck performance - #40925

Summary

• add explicit variance annotations around the Effect Drizzle query graph
• enable persistent incremental metadata for Core's source and tests configs
• make Core source a declaration-emitting composite project consumed by the tests/scripts config
• make TUI consume Core declarations through a project reference
• make internal migration, error, and plugin types portable for declaration emit

Performance

Measured in packages/core on Linux with 2 AMD EPYC 9554P cores and Bun 1.3.14:

The clean build is slower because it emits the Core declaration boundary. Normal edit/typecheck feedback is substantially faster because build mode can compare the source declaration signature and skip the downstream tests/scripts project when public types are unchanged.

The variance annotations independently reduced clean Core type instantiations by roughly 264k and improved the original clean median by about 3.9%.

TUI results:

The TUI program drops from 3,441 files to 1,988 files and resolves zero Core source files. Its package script builds Core declarations first for direct-package correctness, while Turbo orders the Core typecheck task before TUI to avoid concurrent declaration writes.

Validation

• bun turbo typecheck --concurrency=1 (32/32 tasks passed)
• bun turbo typecheck --filter=@opencode-ai/tui --concurrency=1 --force
• focused instruction/session tests (40 passed)
• focused provider and database migration tests (28 passed)