[codex] Speed up numeric array guard cache hits

[andrewtdiz]

Stacked on #5307.

Summary

• Add a pre-classification numeric-array observation builder for get/set guard-cache hits.
• Skip full classify_array work on exact monomorphic numeric-array guard-cache hits.
• Preserve the existing full classify and guard_observe fallback for miss, stale, mismatch, nonnumeric, and layout-mismatch paths.
• Add a runtime test that compares fast observations against the existing classifier, and log the benchmark cycle.

Benchmark Impact

Baseline: #5307 / 6a01499d4f.

• Matrix direct median: 1239ms -> 398ms, 67.9% faster, checksum 41079519680.
• Matrix quick: 1228ms -> 407ms, 66.9% faster.
• Nested compare: 662ms -> 225ms, 66.0% faster.
• Perf direct: 4.49B -> 1.44B cycles; 16.74B -> 7.03B instructions; 3.09B -> 1.57B branches.
• Trace: get/set guard pass counts unchanged, with 0 get/set failures.

Validation

• cargo fmt --check
• git diff --check
• cargo test -p perry-runtime typed_feedback_numeric_array
• cargo test -p perry-runtime typed_feedback
• cargo test -p perry-codegen --test typed_feedback
• cargo test -p perry-codegen --test typed_shape_descriptors
• PERRY_BIN=target/release/perry python3 tests/test_typed_feedback_runtime_evidence.py
• tests/test_benchmark_output_verifier.sh
• cargo build --release
• benchmarks/quick.sh
• benchmarks/compare.sh --quick --runs 3 --warn-only --json-out /tmp/perry-guard-precheck-final2.json
• Direct matrix compile/run/trace/perf commands are recorded in PERF_RUN_LOG.md.

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[proggeramlug]

Closing as superseded. Since this codex stack was cut, main advanced 52+ commits and independently evolved the same hot codegen/runtime paths. This PR is one link in a 13-deep linear stack that conflicts with diverged, correctness-sensitive codegen and was never reviewed; landing it would mean rebasing the whole stack. Per-PR judgement was done before closing.

Specific: main already uses direct-mapped inline caches on the hot object paths (crates/perry-runtime/src/object/mod.rs:1098, alloc.rs:362, field_get_set.rs:5193). The typed-feedback array-guard cache variant here is the only arguably net-new piece, but it's entangled with main's diverged typed_feedback.rs and unreviewed — better re-proposed fresh against current main if it still measures as a win.