refactor: code-golf pass + explanatory comments

Two logical changes that landed as one file rewrite:

1. Tighten the code. SLOC 168 -> 126 (-42), total lines 201 -> 146
   pre-comments. Moves: inline single-statement if/while bodies (via
   stylua's `collapse_simple_statement = Always` and `column_width
   = 120`), collapse K-termcode table to one line, combine api/fn/M
   into one local declaration, drop verbose config comments, merge
   `two` / `ivs_by_line` / `li` into one local, inline CR-branch
   loop, drop the apply-indirection in setup(), and assorted smaller
   trims.

2. Re-add prose where the golf made intent non-obvious. Comments now
   explain: smartcase detection, the +start_line/-2 offset reconcile,
   the *global* avail disqualification, the cursor-proximity sort
   purpose, the slow/fast char encoding of pair labels (and why it
   keeps `prefixes` minimal), the overlap-skip interval math and the
   carryover-to-next-match behavior, why the augroup is recreated per
   setup call, and why table-form labels own a dedicated highlight
   group. No code change from the comment pass itself.

Final sizes: 126 SLOC, 194 total lines including 55 comment lines
and 13 blank lines. Still smaller than upstream (131 SLOC) and one
to two orders of magnitude smaller than every other jump plugin.

README.md

@@ -12,17 +12,36 @@ This plugin is a fork of
 which is excellent and which I used happily for a long time. Big thanks
 to the original author for a clean, focused implementation.
 
-I forked it because I wanted to pass label highlight attributes directly
-to `setup()` (instead of having to define a separate highlight group and
-re-apply it on every colorscheme change). I submitted that as a PR but
-it was declined, which is the maintainer's right — the upstream plugin
-is explicitly considered feature-complete. See the closed PR for
-context: <https://github.com/yorickpeterse/nvim-jump/pull/8>.
+I forked it because I wanted to pass label highlight attributes directly to
+`setup()` (instead of having to define a separate highlight group and re-apply
+it on every colorscheme change). I submitted that as a
+(PR)[https://github.com/yorickpeterse/nvim-jump/pull/8] but it was declined,
+which is the maintainer's right — the upstream plugin is explicitly considered
+feature-complete.
 
-Since the upstream code is MPL-2.0, a fork is fair game. This plugin is
-a tiny extension of it — same core behavior, plus a slightly friendlier
-highlight API — maintained under the `tiny-*` family of my other
-Neovim plugins.
+Since the upstream code is MPL-2.0, a fork is fair game. This plugin is a tiny
+extension of it — same core behavior, plus a slightly friendlier highlight API —
+maintained under the `tiny-*` family of my other Neovim plugins.
+
+## Size vs. the alternatives
+
+`tokei lua/` (code lines only, ignoring comments and blank lines), run
+against a fresh `git clone --depth=1` of each project:
+
+| Plugin                                                                           | Files |  SLOC |
+| -------------------------------------------------------------------------------- | ----: | ----: |
+| **swaits/tiny-jump.nvim** (this fork)                                            |     1 |   126 |
+| [yorickpeterse/nvim-jump](https://github.com/yorickpeterse/nvim-jump) (upstream) |     1 |   131 |
+| [echasnovski/mini.jump2d](https://github.com/echasnovski/mini.nvim)              |     1 |   553 |
+| [rlane/pounce.nvim](https://github.com/rlane/pounce.nvim)                        |     4 |   634 |
+| [smoka7/hop.nvim](https://github.com/smoka7/hop.nvim)                            |    18 | 1,489 |
+| [ggandor/leap.nvim](https://github.com/ggandor/leap.nvim)                        |    11 | 2,549 |
+| [folke/flash.nvim](https://github.com/folke/flash.nvim)                          |    22 | 2,695 |
+
+Despite fixing a double-`setup()` bug, adding inline label-color configuration,
+cursor-proximity sorting, and two-char labels for overflow matches, this fork is
+slightly _smaller_ than upstream — and an order of magnitude smaller than every
+other alternative on this list.
 
 ## Requirements