Rewire server and probod for compliance portal API

Mount the compliance portal mux on trust center hosts, drop the
legacy trust web server, and share response header helpers.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/server/response_headers.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package server
+
+import "net/http"
+
+const strictTransportSecurityValue = "max-age=31536000; preload"
+
+func ApplyExtraHeaders(w http.ResponseWriter, extraHeaderFields map[string]string) {
+	for key, value := range extraHeaderFields {
+		w.Header().Set(key, value)
+	}
+}
+
+func NewSecurityHeadersMiddleware(extraHeaderFields map[string]string) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Strict-Transport-Security", strictTransportSecurityValue)
+			ApplyExtraHeaders(w, extraHeaderFields)
+
+			next.ServeHTTP(w, r)
+		})
+	}
+}