Header limit of 32 KiB, upstream URL checks, build and run scripts

The request line and headers are now refused above 32 KiB exactly: Go's
server reads 4 KiB past MaxHeaderBytes, so that is set to 28 KiB, and
the tests try exactly 32 KiB and one byte more. SWWAF_UPSTREAM_URL now
needs a host, and a given port must be from 1 to 65535. make build and
make run call script/build and script/run.

Model: opus-5-5

Makefile

@@ -4,10 +4,6 @@
 # per the scripts-to-rule-them-all pattern (see the Entrypoints section
 # of README.md). build and run are for working on the code by hand.
 
-# The version the binary reports. It comes from git, so it is computed
-# here on the host; the Dockerfile is passed it as a build argument.
-VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo unknown)
-
 bootstrap:
 	@script/bootstrap
 
@@ -36,8 +32,7 @@ hooks:
 	@script/install-precommit
 
 build:
-	go build -trimpath -ldflags "-X main.Version=$(VERSION)" \
-		-o bin/smallwebwaf ./cmd/smallwebwaf
+	@script/build
 
-run: build
-	./bin/smallwebwaf
+run:
+	@script/run