fix: fix value bit corruption in right_shift

[stringhandler]

Yet another option to solve #337

The tests are actually generated by Claude. The comments are a bit wordy, so happy to try clean it up if it bothers anyone.

The interesting thing to note is that the bug is not as a result of from_padded_bits, as apoelstra (and myself) suspected. Upon adding the two regression tests from #339, prune_regression_337_1 still fails, indicating another bug in from_padded_bits.

However, prune_regression_337_2 passes on this PR without any changes to from_padded_bits. The tests added in this PR also reproduce the error without calling from_padded_bits.

I have also tried to keep the optimization of not cloning the array if the bit is already equal to new_bit and added it to the true case as well.

For those interested here are the before and after benchmarks. Nothing jumps out at me as a huge improvement or degradation.

BEFORE (Commit f84b09d)

test node::redeem::benches::decode_fixed_program          ... bench:      46,840.83 ns/iter (+/- 596.58)
test value::benches::bench_value_create_512_256           ... bench:      60,676.67 ns/iter (+/- 285.67)
test value::benches::bench_value_create_512_256_compact   ... bench:       3,226.49 ns/iter (+/- 73.52)
test value::benches::bench_value_create_512_256_padded    ... bench:       3,277.02 ns/iter (+/- 108.64)
test value::benches::bench_value_create_64k               ... bench:     669,047.50 ns/iter (+/- 4,790.50)
test value::benches::bench_value_create_64k_compact       ... bench:      34,772.54 ns/iter (+/- 3,966.75)
test value::benches::bench_value_create_64k_padded        ... bench:      33,474.00 ns/iter (+/- 3,886.75)
test value::benches::bench_value_create_deep_some         ... bench:     402,400.62 ns/iter (+/- 3,995.75)
test value::benches::bench_value_create_deep_some_compact ... bench:     145,885.00 ns/iter (+/- 1,446.33)
test value::benches::bench_value_create_deep_some_padded  ... bench:       1,224.16 ns/iter (+/- 4.50)
test value::benches::bench_value_create_u2048             ... bench:     469,603.75 ns/iter (+/- 6,750.75)
test value::benches::bench_value_create_u2048_compact     ... bench:       2,117.00 ns/iter (+/- 7.90)
test value::benches::bench_value_create_u2048_padded      ... bench:       2,063.22 ns/iter (+/- 11.30)
test value::benches::bench_value_create_u64               ... bench:          22.49 ns/iter (+/- 0.32)
test value::benches::bench_value_create_u64_compact       ... bench:         165.02 ns/iter (+/- 1.33)
test value::benches::bench_value_create_u64_padded        ... bench:         114.52 ns/iter (+/- 0.88)
test value::benches::bench_value_display_512_256          ... bench:      69,926.25 ns/iter (+/- 804.88)
test value::benches::bench_value_display_64k              ... bench:     707,050.00 ns/iter (+/- 10,249.00)
test value::benches::bench_value_display_deep_some        ... bench:      44,677.50 ns/iter (+/- 727.31)
test value::benches::bench_value_display_u2024            ... bench:      44,629.52 ns/iter (+/- 341.24)
test value::benches::bench_value_display_u64              ... bench:         351.55 ns/iter (+/- 2.40)

AFTER (c70e3ed)

test node::redeem::benches::decode_fixed_program          ... bench:      47,575.83 ns/iter (+/- 1,888.92)
test value::benches::bench_value_create_512_256           ... bench:      62,040.00 ns/iter (+/- 684.18)
test value::benches::bench_value_create_512_256_compact   ... bench:       3,091.83 ns/iter (+/- 19.26)
test value::benches::bench_value_create_512_256_padded    ... bench:       3,034.38 ns/iter (+/- 17.38)
test value::benches::bench_value_create_64k               ... bench:     671,748.75 ns/iter (+/- 4,494.75)
test value::benches::bench_value_create_64k_compact       ... bench:      32,111.70 ns/iter (+/- 5,517.22)
test value::benches::bench_value_create_64k_padded        ... bench:      32,177.62 ns/iter (+/- 7,199.71)
test value::benches::bench_value_create_deep_some         ... bench:     401,901.88 ns/iter (+/- 4,945.75)
test value::benches::bench_value_create_deep_some_compact ... bench:     145,748.00 ns/iter (+/- 833.20)
test value::benches::bench_value_create_deep_some_padded  ... bench:       1,205.44 ns/iter (+/- 5.89)
test value::benches::bench_value_create_u2048             ... bench:     482,537.50 ns/iter (+/- 8,726.38)
test value::benches::bench_value_create_u2048_compact     ... bench:       2,169.61 ns/iter (+/- 7.86)
test value::benches::bench_value_create_u2048_padded      ... bench:       2,075.53 ns/iter (+/- 16.34)
test value::benches::bench_value_create_u64               ... bench:          32.03 ns/iter (+/- 0.91)
test value::benches::bench_value_create_u64_compact       ... bench:         162.57 ns/iter (+/- 1.75)
test value::benches::bench_value_create_u64_padded        ... bench:         113.74 ns/iter (+/- 0.67)
test value::benches::bench_value_display_512_256          ... bench:      74,847.14 ns/iter (+/- 1,099.57)
test value::benches::bench_value_display_64k              ... bench:     709,160.00 ns/iter (+/- 12,038.00)
test value::benches::bench_value_display_deep_some        ... bench:      43,401.18 ns/iter (+/- 559.59)
test value::benches::bench_value_display_u2024            ... bench:      44,913.00 ns/iter (+/- 477.15)
test value::benches::bench_value_display_u64              ... bench:         357.24 ns/iter (+/- 7.69)

[apoelstra]

Can you swap the two commits? I appreciate having them separate but I'd like them both to pass tests in the git history.

[apoelstra]

c70e3ed looks great! This is a simple, elegant fix (and way simpler than the stuff we were trying to do with the constructors, and with attempting to enforce an "all padding is 0" invariant).

The tests look good to me. Appreciate the comments, though I suspect they'll wind up being out-of-date if we change anything about our internal representation. We can eventually delete them. But for now let's keep them.

[stringhandler]

swap or squash? Happy to do either, but squashing is easier

[apoelstra]

@stringhandler I'd prefer to swap.

You can swap pretty easily with git rebase -i master then just exchange the two lines.

[stringhandler]

Done

[apoelstra]

ACK b64e1b3; successfully ran local tests