refactor: Use package knowledge for run summaries (#13465)
### Description
Part 10 of the package/scope knowledge completion stack.
Use authoritative task contexts for run summaries, task suggestions,
command detection, and external-dependency hash precomputation. Summary
directories and log paths no longer come from manifest compatibility
fields, while hash bytes remain unchanged.
### Testing Instructions
- `cargo test -p turborepo-run-summary -p turborepo-task-hash`
- `cargo test -p turbo --test dry_run_test --test final_hash_contract
--test run_summary`
