Switch remote deploy to vendored source builds

Move remote deployment to a vendored source bundle built on the target host via Docker so redeploys no longer require local cross-compilation or host Go installation.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

vendor/git.sr.ht/~jackmordaunt/go-toast/v2/tmpl/tmpl.go

@@ -0,0 +1,28 @@
+// Package tmpl wraps several templates that are used to generate notifications.
+//
+// The primary template describes the XML structure that the Windows Runtime expects
+// to consume. The powershell template describes a script that we can use to execute
+// the notification if the Windows Runtime is unavailable.
+//
+// For more information about the xml schema:
+// https://learn.microsoft.com/en-us/uwp/schemas/tiles/toastschema/schema-root
+package tmpl
+
+import (
+	_ "embed"
+	"text/template"
+)
+
+//go:embed xml.go.tmpl
+var xml string
+
+//go:embed powershell.go.tmpl
+var powershell string
+
+// XMLTemplate describes the XML content that the Windows Runtime uses to build
+// toast notifications.
+var XMLTemplate = template.Must(template.New("toast-xml").Parse(xml))
+
+// ScriptTemplate describes the Powershell script that will invoke a toast notification
+// given some XML.
+var ScriptTemplate = template.Must(template.New("script").Parse(powershell))