style: trim verbose comments to concise, self-contained notes

Cut restated "what", domain-glossary framing, cross-file consumption
narration, and against-alternative justification from in-file comments;
keep only non-obvious "why" and load-bearing pointers. Drop the
`generateCompletions` line (a no-op restatement of the upstream default)
and its comment.

modules/tmux/tmux.nix

@@ -3,10 +3,8 @@
   lib,
   ...
 }:
-# tmux for the primary user, configured natively through home-manager. The
-# settings home-manager exposes as options are set here; every setting it has
-# no option for is read verbatim from ./extra.conf. No tmux plugin manager is
-# used.
+# tmux for the primary user, configured through home-manager. Settings without a
+# home-manager option are read from ./extra.conf.
 let
   cfg = config.modules.tmux;
   user = config.user.name;
@@ -21,8 +19,8 @@ in
       prefix = "C-Space";
       keyMode = "vi";
       mouse = true;
-      baseIndex = 1; # windows and panes count from 1.
-      clock24 = true; # 24-hour clock in the clock-mode overlay.
+      baseIndex = 1;
+      clock24 = true;
       escapeTime = 10; # short Esc delay so exiting insert mode in nvim isn't laggy.
       historyLimit = 10000;
       terminal = "tmux-256color";