fix(mir): validate global HIR type metadata

[sanohiro]

Summary

• reject malformed program-global HIR type metadata before any MIR entrypoint publishes partial output
• validate concrete roots, abstract template reachability, reference ranges, scalar widths and lanes, and inline recursive cycles with an iterative graph walk
• preserve header-mediated recursion through heap, dynamic-array, task, and function headers
• add exhaustive mutation/identity owners and a 512-root boundary benchmark

Validation

• scripts/test-pr.sh
• cargo clippy --workspace --all-targets --locked -- -D warnings
• cargo test -p align_mir
• cargo test -p align_driver --test per_unit_codegen
• cargo clippy -p align_mir --all-targets --locked -- -D warnings
• bench/library_boundary/run.sh (mir-global-type-validation: 0.240 ms/lower for 514 total HIR types)

Review

• align-self-review: no unresolved findings
• fresh adversarial preflight: one P2 test-coverage finding, closed by adding all ledger-required header-cycle twins across all four lowering entrypoints
• final preflight verdict: clean