Restore Markdown formatting in fmt/fmt-check and pin prettier (closes #19)

script/fmt and script/fmt-check now run gofmt for Go and prettier for
Markdown; fmt-check reports each independently. prettier is pinned at
3.8.1 by package.json/yarn.lock (integrity hash); .prettierrc and
.prettierignore are the house settings copied from the prompts repo.
script/bootstrap installs node and yarn from the host package manager
and runs `yarn install --frozen-lockfile`.

The Markdown check runs in CI via the Dockerfile build stage, where
bootstrap provides prettier; it is removed from the lint stage because
the golangci-lint image has no node. JS manifests are copied before
bootstrap so the yarn layer caches, and node_modules is dockerignored.

node is an unpinned host runtime like git/make/go: nvm's glibc node does
not run on the musl/Alpine build image, so the canonical nvm route is
not usable here; prettier is the hash-pinned formatter. The wholesale
Markdown reformat follows in the next commit.

Model: opus-4-8

script/bootstrap

@@ -11,6 +11,12 @@ set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+# yarn provides prettier, which formats Markdown. yarn is a tool, like
+# node/git/make/go below; the reference that governs formatting output is
+# prettier, pinned by yarn.lock's integrity hash and installed by
+# `yarn install --frozen-lockfile`.
+YARN_VERSION="1.22.22"
+
 PKGMGR=""
 SUDO=""
 APT_UPDATED=""
@@ -58,6 +64,21 @@ missing() {
     ! command -v "$1" >/dev/null 2>&1
 }
 
+ensure_node() {
+    if ! missing node; then return 0; fi
+    pkg_install nodejs nodejs node nodejs
+}
+
+ensure_yarn() {
+    if ! missing yarn; then return 0; fi
+    if ! missing corepack; then
+        corepack enable >/dev/null 2>&1 || true
+        corepack prepare "yarn@$YARN_VERSION" --activate
+    else
+        pkg_install yarn yarn yarn yarn
+    fi
+}
+
 main() {
     cd "$ROOT"
 
@@ -71,6 +92,16 @@ main() {
     if missing make; then pkg_install gnumake make make make; fi
     if missing go; then pkg_install go golang go go; fi
 
+    # node runs prettier and is an unpinned host tool for the same reason
+    # git/make/go are: it comes from the host package manager, whatever
+    # version it ships. It is not installed via nvm the way the canonical
+    # template does, because nvm's prebuilt node is glibc-linked and does
+    # not run on this repo's musl/Alpine build image. prettier — the tool
+    # whose version affects formatting output — is pinned by yarn.lock.
+    ensure_node
+    ensure_yarn
+    yarn install --frozen-lockfile
+
     # Linting runs via docker only (script/lint), so docker is a lint
     # prerequisite rather than something bootstrap installs. Warn, do
     # not fail: everything except `make lint` — and, through it,

script/fmt

@@ -1,12 +1,23 @@
 #!/bin/sh
-# script/fmt: format all files (writes).
+# script/fmt: format all files (writes). gofmt for Go, prettier for
+# Markdown. prettier is the pinned devDependency in package.json/
+# yarn.lock; script/bootstrap installs it (see run_prettier).
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+run_prettier() {
+    if ! command -v yarn >/dev/null 2>&1; then
+        echo "fmt: yarn not found; run script/bootstrap first" >&2
+        exit 1
+    fi
+    yarn run prettier "$@"
+}
+
 main() {
     cd "$ROOT"
     gofmt -s -w .
+    run_prettier --write '**/*.md' --tab-width 4 --prose-wrap always
 }
 
 main "$@"

script/fmt-check

@@ -1,18 +1,37 @@
 #!/bin/sh
 # script/fmt-check: check formatting (read-only). Same scope as
-# script/fmt, but fails instead of writing.
+# script/fmt: gofmt for Go, prettier for Markdown. Both run every time
+# and each reports independently, so a failure names which formatter is
+# unhappy; the script exits non-zero if either found unformatted files.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+run_prettier() {
+    if ! command -v yarn >/dev/null 2>&1; then
+        echo "fmt-check: yarn not found; run script/bootstrap first" >&2
+        exit 1
+    fi
+    yarn run prettier "$@"
+}
+
 main() {
     cd "$ROOT"
+    rc=0
+
     files="$(gofmt -s -l .)"
     if [ -n "$files" ]; then
         echo "gofmt: files not formatted:" >&2
         echo "$files" >&2
-        exit 1
+        rc=1
     fi
+
+    if ! run_prettier --check '**/*.md' --tab-width 4 --prose-wrap always; then
+        echo "prettier: Markdown not formatted; run make fmt" >&2
+        rc=1
+    fi
+
+    exit "$rc"
 }
 
 main "$@"