Shim make dev and make build, format backend/ markdown (closes #28)

make dev ran yarn dev inline and there was no make build. Both are now
shims, over script/dev and the new script/build. .prettierignore stops
leaving out backend/, so backend/README.md is formatted and checked;
backend/.golangci.yml is left out by name instead: it is the org
standard file whose sha256 backend/script/lint checks, and prettier
would reindent it. .claude/ stays in .prettierignore, as git does not
ignore it. script/install-precommit and the date on bootstrap's pins go
back to the org model; bootstrap, fmt and fmt-check keep what the Go
backend and eslint need, each with a comment saying so.

Model: opus-5-5

script/install-precommit

@@ -8,8 +8,8 @@ ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 main() {
     cd "$ROOT"
     hook=".git/hooks/pre-commit"
-    printf '#!/bin/sh\nset -e\nscript/precommit\n' > "$hook"
-    chmod +x "$hook"
+    printf '#!/bin/sh\nset -e\nscript/precommit\n' > .git/hooks/pre-commit
+    chmod +x .git/hooks/pre-commit
     echo "pre-commit hook installed: runs script/precommit"
 }