fix(history): raise authoritative graph limit to 5 GiB

[forhappy]

Summary

• raise the immutable-history aggregate authoritative-evidence ceiling from 512 MiB to 5 GiB
• keep existing per-key, per-value, per-tree, JSON-depth, job, and diagnostic limits unchanged
• document the compatibility boundary for older Compass readers
• add regression coverage for the exact 616,211,608-byte graph that previously failed

Real-repository verification

Rebuilt the Compass base revision from PR #308 without exclusions using the updated binary. The complete realization validated and published successfully with:

• 55,714 nodes
• 135,550 edges
• 379,130 program facts
• 31,144 program summaries

Verification

• cargo fmt --all -- --check
• cargo test -p compass-history --locked
• cargo clippy -p compass-history --all-targets --all-features --locked -- -D warnings
• cargo clippy --workspace --lib --bins --locked -- -D warnings
• cargo test --workspace --lib --bins --locked
• sh scripts/check_product_boundary.sh