treefmt: apply prettier

Pure `nix fmt` output from the commit before this one — no hand edits.
203 files: 52 md, 42 tsx, 32 js, 32 css, 21 ts, 13 html, 8 json, 3 mjs.

Reproduce with `nix develop -c nix fmt` on the parent commit; the result
should be byte-identical to this tree.

None of the 13 `.prettierignore` entries appears here — verified by
intersecting the changed-file list against the ignore file, with a
control proving the intersection finds a match when one exists.

docs/process/pr-review-gate.md

@@ -8,7 +8,7 @@ human review that already happened.
 
 Whether a PR can merge, and what counts toward "can", is configured
 per repo in its branch-protection settings — not a fact true of every
-hive or every repo. The pieces a repo *can* require:
+hive or every repo. The pieces a repo _can_ require:
 
 - **CI is green** — the repo's required status checks pass on the
   PR's current head commit, if the repo requires any.
@@ -40,8 +40,8 @@ independently.
 
 Auto-merge isn't "no human ever looked at this." Whoever arms it has
 already judged the PR sound at a coarse level — the signal it sends is
-roughly *"apart from maybe minor tweaks a reviewer can still catch,
-I think this is fine."* That's the human-in-the-loop step, and it
+roughly _"apart from maybe minor tweaks a reviewer can still catch,
+I think this is fine."_ That's the human-in-the-loop step, and it
 already happened. No large changes are expected to surface after
 that point — a reviewer's job past that point is to flag it if one
 does, not to assume none ever will.