Initial commit

CalDAV and CardDAV checkers sharing a single Go module. Discovery follows
RFC 6764 (/.well-known + SRV/TXT), authenticated probes cover principal,
home-set, collections and a minimal REPORT query on top of go-webdav.
Common shape in internal/dav/; CalDAV adds a scheduling rule.

Surfaces its context URL (and each secure-SRV target) as TLS endpoints via
the EndpointDiscoverer interface, so the dedicated TLS checker can pick
them up without re-parsing observations.

HTML report foregrounds common misconfigs (well-known returning 200,
missing SRV, plaintext-only SRV, missing DAV capability, skipped auth
phase) as action-item callouts before the full phase breakdown.

cmd/checker-caldav/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"flag"
+	"log"
+
+	"git.happydns.org/checker-dav/caldav"
+	"git.happydns.org/checker-sdk-go/checker/server"
+)
+
+// Version is injected at link time via -ldflags "-X main.Version=...".
+var Version = "custom-build"
+
+var listenAddr = flag.String("listen", ":8080", "HTTP listen address")
+
+func main() {
+	flag.Parse()
+	caldav.Version = Version
+	srv := server.New(caldav.Provider())
+	if err := srv.ListenAndServe(*listenAddr); err != nil {
+		log.Fatalf("server error: %v", err)
+	}
+}

cmd/checker-carddav/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"flag"
+	"log"
+
+	"git.happydns.org/checker-dav/carddav"
+	"git.happydns.org/checker-sdk-go/checker/server"
+)
+
+// Version is injected at link time via -ldflags "-X main.Version=...".
+var Version = "custom-build"
+
+var listenAddr = flag.String("listen", ":8080", "HTTP listen address")
+
+func main() {
+	flag.Parse()
+	carddav.Version = Version
+	srv := server.New(carddav.Provider())
+	if err := srv.ListenAndServe(*listenAddr); err != nil {
+		log.Fatalf("server error: %v", err)
+	}
+}