chore: rename to namespace padding

[rootulp]

Closes #1926

[codecov-commenter]

Codecov Report

Merging #1929 (6f86029) into main (376a1d4) will decrease coverage by 0.64%.
The diff coverage is 16.66%.

@@            Coverage Diff             @@
##             main    #1929      +/-   ##
==========================================
- Coverage   21.85%   21.21%   -0.64%     
==========================================
  Files         117      120       +3     
  Lines       13304    13693     +389     
==========================================
- Hits         2907     2905       -2     
- Misses      10107    10498     +391     
  Partials      290      290              

Impacted Files	Coverage Δ
pkg/shares/share_splitting.go	41.93% <0.00%> (ø)
pkg/square/builder.go	77.22% <0.00%> (ø)
pkg/shares/split_sparse_shares.go	38.46% <25.00%> (ø)

... and 12 files with indirect coverage changes