Re-vendor the shared files from sneak/prompts at dd4027b (closes #113)

The shared files are the sneak/prompts copies at dd4027b, plus this
repository's own entries. make lint and make test each build one
Dockerfile phase without the cache, both covering the frontend; the
builder stage waits on both and takes its version from git describe
unless VERSION is given. The test phase keeps Go's module and build
caches in memory, out of the image make test tags. golangci-lint moves
to v2.14.0 with the new .golangci.yml; one test spells X-Request-ID as
canonicalheader asks. prettier formats only JavaScript, CSS, HTML and
Markdown, so .golangci.yml stays as fetched. script/fmt and
script/fmt-check put ~/.local/bin on PATH. script/bootstrap keeps a Go
only if it is exactly GO_VERSION, and re-checks the go on PATH after
installing.

Model: opus-5-5

script/test

@@ -1,17 +1,19 @@
 #!/bin/sh
-# script/test: run the test suite for the whole repo: the frontend at
-# the repo root, then the Go backend in backend/. Each half has its own
-# 30-second limit, and there is none around both: from a cold Go build
-# cache, compiling the backend's tests with the race detector can take
-# 30 seconds on its own, and Go's -timeout leaves the compile out.
+# script/test: run the test suite. Testing is a phase of the Dockerfile
+# and this builds that phase alone, on the same terms as script/lint:
+# --target because a phase that is not the last stage is built only when
+# named, --no-cache because a cached test layer is a test that did not
+# run, and a tag so each build replaces the previous image.
 set -eu
 
-ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    script/frontend-test
-    backend/script/test
+    docker build --no-cache \
+        --target test \
+        -t "$("$SCRIPT_DIR/projectname")-test" .
 }
 
 main "$@"