Optimize dense numeric array fill loops

[TheHypnoo]

Summary

• lower compiler-proven dense numeric array fill loops into bulk runtime helpers
• add raw-f64 bulk fill helpers for constant and iota writes, including arr.length-bounded variants
• gate typed feedback collection in normal runtime unless feedback tracing is enabled

Benchmarks

Median of 3 runs with --no-auto-optimize, compared to the prior typed-feedback baseline:

• 03_array_write.ts: 3270 ms -> 4 ms (817.5x faster; faster than Node 9 ms and Bun 6 ms locally)
• 04_array_read.ts: 3388 ms -> 174 ms (19.5x faster)
• 10_nested_loops.ts: 4300 ms -> 307 ms (14.0x faster)
• 11_prime_sieve.ts: 549 ms -> 47 ms (11.7x faster)
• 16_matrix_multiply.ts: 8854 ms -> 581 ms (15.2x faster)
• bench_numeric_array_numeric.ts: 3651 ms -> 243 ms (15.0x faster)
• bench_array_grow.ts: 523 ms -> 125 ms (4.2x faster)

Current local comparison after this change (Perry / Node / Bun, median ms):

• 03_array_write.ts: 4 / 9 / 6
• 06_math_intensive.ts: 51 / 51 / 52
• 05_fibonacci.ts: 318 / 1029 / 553
• 15_mandelbrot.ts: 23 / 25 / 29

Remaining gaps to target next:

• 09_method_calls.ts: Perry 7338 ms vs Node 11 ms vs Bun 19 ms
• 16_matrix_multiply.ts: Perry 581 ms vs Node/Bun 35 ms
• bench_numeric_array_numeric.ts: Perry 243 ms vs Node/Bun 5 ms
• 04_array_read.ts: Perry 174 ms vs Node 12 ms vs Bun 19 ms

Validation

• cargo check -p perry-codegen --quiet
• cargo test -p perry-runtime numeric_array --quiet
• cargo test -p perry-runtime typed_feedback --quiet
• cargo build -p perry --release --quiet
• cargo build -p perry-runtime --release --quiet
• rustfmt --check on the four touched source files
• git diff --check
• Perry vs Node smoke comparisons for array write/read, numeric arrays, grow, array methods/slice/object arrays, guarded raw numeric arrays, and bulk-fill length semantics

Note: cargo fmt -- --check currently reports unrelated pre-existing formatting diffs in perry-codegen/perry-hir files. cargo test --workspace cannot complete on this machine because pkg-config cannot find the system gtk4 and graphene-gobject-1.0 libraries required by gdk4-sys/graphene-sys.