Implement direct owned JSON records

[sanohiro]

Summary

• implement Request 9 direct-owned JSON records from the contract merged in docs(json): design owned declared records #851
• support string, Option<string>, and array<string> fields with free-standing decode ownership, canonical encode, bounded encode, recursive Drop, and recoverable failure cleanup
• carry deterministic target-bound owned-JSON descriptors through interface artifacts and the unit cache, with independent malformed-record validation
• extend the runtime ABI, checked HIR, MIR, LLVM lowering, and focused owner matrices for formation, control flow, failure prefixes, integer widths, generic substitution, concurrency, and the full 153-operation overlap matrix

Review finding closure

• route JsonOwnedEncode and JsonOwnedEncodeBounded through MIR's stack-safe out-of-line dispatcher and recognize nested owned template spines; a structural deep-expression tripwire now pins the complete sibling set
• update every standalone library-boundary benchmark literal for the current IFnSig and InterfaceSummary records and refresh its independent lockfile
• close the two candidate Clippy warnings in owned runtime cleanup

Verification

• scripts/cargo.sh test -p align_mir owned_json_encoders_use_stack_safe_dispatch
• scripts/cargo.sh check --manifest-path bench/library_boundary/Cargo.toml
• scripts/cargo.sh test -p align_driver --test m5_owned_json
• CARGO_TARGET_DIR=target/clippy scripts/cargo.sh clippy --workspace --lib --bins
• scripts/lint-ratchet.sh
• scripts/pre-pr.sh with the Request 9 end-to-end owner target, bounded gate, and locked workspace Clippy