implement live-reloading dev server

Squashed commit of the following:

commit 02f077432202af4d633eb2cad81dfdaa6921317f
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 21:09:14 2024 +0200

    builder: only remove output directory if set and in dev mode

commit 47001e01c55fa6e74aafeda04ebc3e4e7c47eba0
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 21:03:37 2024 +0200

    implement live reload on dev server

commit 411ec969f61e4b73439f1c54ea29f75135ecc618
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:59:26 2024 +0200

    server: implement graceful shutdown

commit 5400132eb6eb1b638e0b3fd4265f51611c92d473
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:41:07 2024 +0200

    add some debug logs

commit 3c9b678197c044603950232d222f501ef74d7873
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:39:09 2024 +0200

    prefix log output with executable name

commit 300e24c179e390e9d3f5aeab4471c97f17f1fa64
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:29:42 2024 +0200

    don't panic inside internal packages, return error instead

commit fe2715d330402ad67fe866471bed89c7238ad2ec
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Fri Apr 26 01:18:29 2024 +0200

    config: use a table to configure CSP headers

commit d012553aaf78a436fa8871830b5d720a9e292d4b
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 17:13:39 2024 +0200

    dev: create basic dev server to build and serve from a temporary directory

commit a1d11d3e69650d9b43ca1b1d7b7ccc05a808d5c1
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 13:02:22 2024 +0200

    remove unused redirect_other_hostnames config option

commit fd67b19b5c7f76f0c3579e8a05ef20a618e90be7
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 12:58:53 2024 +0200

    server: make port a string, which is what go uses

commit c798e8e736c0649008cade337158399470a9099b
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 12:58:33 2024 +0200

    config: remove unused port variable

commit f94882b9001f3b0855e26b26b4a84b96e3deb22b
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 12:49:10 2024 +0200

    re-organise module layout

1 files changed, 0 insertions, 55 deletions

diff --git a/cmd/server/logging.go b/cmd/server/logging.go
deleted file mode 100644
index 601baab..0000000
--- a/cmd/server/logging.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"io"
-	"net/http"
-)
-
-type loggingResponseWriter struct {
-	http.ResponseWriter
-	statusCode int
-}
-
-func (lrw *loggingResponseWriter) WriteHeader(code int) {
-	lrw.statusCode = code
-	// avoids warning: superfluous response.WriteHeader call
-	if lrw.statusCode != http.StatusOK {
-		lrw.ResponseWriter.WriteHeader(code)
-	}
-}
-
-func NewLoggingResponseWriter(w http.ResponseWriter) *loggingResponseWriter {
-	return &loggingResponseWriter{w, http.StatusOK}
-}
-
-type wrappedHandlerOptions struct {
-	defaultHostname string
-	logger          io.Writer
-}
-
-func wrapHandlerWithLogging(wrappedHandler http.Handler, opts wrappedHandlerOptions) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		scheme := r.Header.Get("X-Forwarded-Proto")
-		if scheme == "" {
-			scheme = "http"
-		}
-		host := r.Header.Get("Host")
-		if host == "" {
-			host = opts.defaultHostname
-		}
-		lw := NewLoggingResponseWriter(w)
-		wrappedHandler.ServeHTTP(lw, r)
-		statusCode := lw.statusCode
-		fmt.Fprintf(
-			opts.logger,
-			"%s %s %d %s %s %s\n",
-			scheme,
-			r.Method,
-			statusCode,
-			host,
-			r.URL.Path,
-			lw.Header().Get("Location"),
-		)
-	})
-}