Re-vendor the canonical files from sneak/prompts at dd4027b (closes #171)

.dockerignore, .gitignore, .prettierignore and REPO_POLICIES.md are
copied from sneak/prompts at dd4027b; .editorconfig, check.yml and
.prettierrc already matched. This repository's build artifacts follow
the copied content in .gitignore and, anchored, in .dockerignore. The
scripts follow the new policy: check runs fmt-check, cibuild bootstraps
and runs check before the image build, fmt and fmt-check find the
pinned yarn under nvm, and the image's last stage marks /app safe for
git. The build-context test expects the new pattern forms.

Judgement call: script/precommit runs lint and fmt-check without the tests, so the README's red-phase test commit can still land; the policy allows that form only where local testing is impossible.
Not applicable: the issue's .golangci.yml entries; this TypeScript repository has none.

Model: opus-5-5

README.md

@@ -137,16 +137,15 @@ alpine. We provide:
 - `script/lint` — run eslint and a prettier check, by building the `lint` phase
   of the `Dockerfile`; requires docker (see Linting and testing below)
 - `script/fmt` — format all files with prettier (writes)
-- `script/fmt-check` — check formatting on the host (read-only); standalone, and
-  not called by `script/check` or `script/precommit`, because `script/lint`
-  already checks formatting in the container
-- `script/check` — run all checks: `test`, `lint` (our own extension)
+- `script/fmt-check` — check formatting on the host (read-only)
+- `script/check` — run all checks: `test`, `lint`, `fmt-check` (our own
+  extension)
 - `script/docker` — build the image, tagged via `script/projectname`
-- `script/cibuild` — build the image (what CI runs); its last stage depends on
-  the `lint` and `test` phases, so this one build lints, tests and compiles
+- `script/cibuild` — what CI runs: `script/bootstrap`, then `script/check`, then
+  the image build
 - `script/precommit` — run by the git pre-commit hook (our own extension); runs
-  `script/lint`, which checks both lint and formatting, but deliberately not the
-  tests, so the TDD red-phase commit can land
+  `script/lint` and `script/fmt-check` but deliberately not the tests, so the
+  TDD red-phase commit can land
 - `script/install-precommit` — installs the git pre-commit hook (our own
   extension); `make hooks` shims to it
 
@@ -162,22 +161,19 @@ script runs the tools on the host: docker is required, and that also works where
 the docker daemon is remote and bind mounts are impossible.
 
 The last stage of the `Dockerfile` compiles the package, and it copies a file
-from each phase, so it cannot be built unless lint and the tests pass. That is
-why `script/cibuild` is a single `docker build`: it runs lint and the tests once
-each and then compiles.
+from each phase, so it cannot be built unless lint and the tests pass. The image
+build in `script/cibuild` therefore runs lint and the tests a second time, after
+`script/check` has run them.
 
 Every `docker build` in `script/` passes `--no-cache`. On an unchanged tree
 Docker would otherwise serve the lint and test steps from cache, nothing would
 run, and the build would still exit 0.
 
-The formatting check is part of the `lint` phase, not a step beside it, so
-`script/check` and `script/precommit` do not call `script/fmt-check` as well;
-that would run prettier a second time over the same tree for the same verdict.
-`script/fmt-check` remains as a standalone entrypoint for asking the formatting
-question on the host. Its verdict matches the container's: prettier is pinned to
-an exact version, installed from `yarn.lock` under `--frozen-lockfile` in both
-places, and reads `.gitignore` as its default ignore file — which is why
-`.dockerignore` keeps `.gitignore` in the build context.
+`script/fmt-check` runs prettier on the host. Its verdict matches the `lint`
+phase's: prettier is pinned to an exact version, installed from `yarn.lock`
+under `--frozen-lockfile` in both places, and reads `.gitignore` as its default
+ignore file — which is why `.dockerignore` keeps `.gitignore` in the build
+context.
 
 ### Version
 
@@ -259,11 +255,10 @@ All work on quak is test-driven. No exceptions.
    history must still show tests landing before (or with) the matching
    implementation.
 8. The pre-commit hook installed by `make hooks` runs `script/precommit`, which
-   runs `script/lint` — eslint and the prettier check, in the container — but
-   not the tests, and so not the full `make check`. This is deliberate so the
-   TDD red-phase commit (failing tests, no implementation yet) can land. The
-   `test` phase is part of the image build, which is what CI executes via
-   `script/cibuild`, so a red branch still cannot reach `next`.
+   runs `script/lint` and `script/fmt-check` but not the tests, and so not the
+   full `make check`. This is deliberate so the TDD red-phase commit (failing
+   tests, no implementation yet) can land. CI executes `script/cibuild`, which
+   runs the tests, so a red branch still cannot reach `next`.
 
 ## Design
 
@@ -995,14 +990,12 @@ documents:
   before the implementation. Tests are the canonical API documentation and must
   be commented thoroughly. `main` and `next` are always green.
 
-- **Required checks before every commit:** `make lint` must pass — that is
-  eslint plus the prettier check, and it builds the `lint` phase of the
-  `Dockerfile`, so it needs docker. The pre-commit hook enforces exactly that.
-  `make check` (which also runs the tests) must pass before merging into `next`.
-  `make fmt-check` is available for a host-side formatting check on its own, but
-  it is not a separate requirement: `make lint` already covers it, and running
-  both would check formatting twice. Never invoke eslint or prettier directly;
-  linting runs in the container only.
+- **Required checks before every commit:** `make lint` and `make fmt-check` must
+  pass. `make lint` is eslint plus the prettier check, and it builds the `lint`
+  phase of the `Dockerfile`, so it needs docker. The pre-commit hook enforces
+  exactly that. `make check` (which also runs the tests) must pass before
+  merging into `next`. Never invoke eslint or prettier directly; linting runs in
+  the container only.
 
 - **Formatting:** prettier with 4-space indents and `proseWrap: always` for
   markdown. Use `make fmt` to format. Use `yarn` not `npm`.