Format Go with gofmt, then golines -m 77 (closes #215)

script/fmt now runs golines -m 77 after gofmt, repeating golines until
it changes nothing, since one pass can leave a line the next splits.
script/fmt-check fails when either would change a file.
script/bootstrap installs golines v0.13.0 with go install, pinned to
its commit, and checks the installed version with go version -m.

The tree is reformatted. The longer lines this makes are fixed by
hand: nolint directives moved onto their own line above the statement,
one string split, and 20 functions over funlen's 80 lines shortened or
split, RunWAF and limitPercentages among them.

Model: opus-5-5

script/fmt

@@ -1,6 +1,6 @@
 #!/bin/sh
-# script/fmt: format all files (writes): the Go code with gofmt, the
-# Markdown with prettier.
+# script/fmt: format all files (writes): the Go code with gofmt and
+# then golines -m 77, the Markdown with prettier.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
@@ -24,9 +24,33 @@ run_yarn() {
         shift && exec yarn "$@"' bash "$NODE_VERSION" "$@"
 }
 
+# The golines that script/bootstrap installed: go install puts it in
+# GOBIN, or in GOPATH/bin when GOBIN is unset.
+golines_path() {
+    gobin="$(go env GOBIN)"
+    golines="${gobin:-$(go env GOPATH)/bin}/golines"
+    if [ ! -x "$golines" ]; then
+        echo "fmt: no golines; run script/bootstrap first" >&2
+        exit 1
+    fi
+    echo "$golines"
+}
+
 main() {
     cd "$ROOT"
+    golines="$(golines_path)"
     gofmt -w cmd internal
+    # One golines pass can leave a line that the next pass splits
+    # further, so run it until it would change nothing.
+    passes=0
+    while [ -n "$("$golines" -m 77 -l cmd internal)" ]; do
+        passes=$((passes + 1))
+        if [ "$passes" -gt 5 ]; then
+            echo "fmt: golines -m 77 still changes files after 5 passes" >&2
+            exit 1
+        fi
+        "$golines" -m 77 -w cmd internal
+    done
     run_yarn run prettier --write '**/*.md' --tab-width 4 --prose-wrap always
 }