Move to the layout REPO_POLICIES.md gives (closes #30)

The Go module moves from backend/ to the root (go.mod, go.sum,
.golangci.yml, cmd/, internal/), the page's source to web/, and nginx's
two files to configs/. backend/ is gone: its LICENSE and .dockerignore
are deleted, and its .gitignore entries, README and scripts are folded
into the root ones. script/build builds the server binary after the
frontend; script/run and script/clean move up from backend/script/;
make test, lint, fmt and fmt-check do what the backend's did. Vite's
root is web/ and it still builds into dist/. go.mod ignores
node_modules/, whose npm packages can ship .go files. script/bootstrap
no longer installs gcc, which only the host Go tests needed.

Model: opus-5-5

Makefile

@@ -1,10 +1,10 @@
-.PHONY: bootstrap setup dev build test lint fmt fmt-check check \
+.PHONY: bootstrap setup dev build run clean test lint fmt fmt-check check \
 	add-dependency tidy frontend-viewport-test docker hooks
 
 # Standard targets are thin shims; the implementations live in script/
 # per the scripts-to-rule-them-all pattern (see the Entrypoints section
 # of README.md). test, lint, fmt, fmt-check and check cover the whole
-# repo: the frontend here and the Go backend in backend/.
+# repo: the frontend in web/ and the Go backend in cmd/ and internal/.
 
 bootstrap:
 	@script/bootstrap
@@ -15,10 +15,17 @@ setup:
 dev:
 	@script/dev
 
-# The frontend only; backend/Makefile's build target builds the Go server.
+# The frontend into dist/ and the netwatch-server binary.
 build:
 	@script/build
 
+# Builds, then runs netwatch-server on port 8080.
+run:
+	@script/run
+
+clean:
+	@script/clean
+
 test:
 	@script/test