docs: spell out kactl macros in doc comments

[cameroncuster]

The main branch publishes headers with kactl macros expanded (update_main.sh runs them through cpp with kactl_macros.hpp), but doc comments pass through the preprocessor untouched — so on main, docstrings referenced vi, pii, ll, sz(...), and rep(...) while the surrounding code showed the expanded forms.

This spells out the macros in all doc comments so the published docstrings match the published code:

• vi → vector<int>
• pii → pair<int, int>
• ll → int64_t
• sz(x) → ssize(x)
• rep(i, a, b) → for (int i = a; i < b; i++)

Deliberately untouched:

• Lambda parameter names vl/vr in seg_tree.hpp / merge_sort_tree.hpp (variables, not macros)
• vl in wildcard_pattern_matching.hpp docs (that file defines using vl = vector<ll>; in code, which survives to main)
• The English word "all" in prose

Comment-only change: 41 files, all 64 changed diff lines are comments; zero code lines touched. Lines that exceeded the 59-column limit after expansion were re-wrapped. clang-format (dev.clang-format) passes on all changed files, and a repo-wide scan confirms no macro tokens remain in any library comment.