Support recursive owned JSON graphs

[sanohiro]

Summary

• extend direct owned JSON support from flat records to recursive record graphs
• carry target-bound V2 owned JSON graph descriptors through HIR, MIR, interfaces, LLVM lowering, and the runtime
• support owned strings and arrays of owned strings inside recursive records
• add exact cycle, depth, malformed-input, cross-unit, cache, and C6 closure coverage

Review fixes

• resolve imported qualified and generic record graphs against complete HIR definitions
• include reachable dependency definition changes in interface identity
• enforce the 128-record path limit for shared DAGs reached through deeper paths
• update the unit-cache schema golden and boundary benchmark to format 8 terminology

Verification

• scripts/pre-pr.sh --reviewer codex --review-log .git/align-review-0e1152925938b987867ff350050e97192dbf47a4.log --findings-fixed -- scripts/cargo.sh test -p align_driver --test m5_owned_json
• focused interface, sema, per-unit, unit-cache, owned JSON, benchmark-check, and lint-ratchet targets

Independent review found four actionable issues; all four were fixed and closed by their owner regressions before the final-SHA preflight.