projection: begin the exact-path public epoch

The public tree and its history contain only the listed paths. Earlier projection history remains preserved internally.

Source-Sha: 913fde029b935671833254797f0f20f1eb9fabba

Policy-Sha: 913fde029b935671833254797f0f20f1eb9fabba

Tree-Digest: 180ae530c1058a2a5c89837bdce2d323ae83e669e38590ca72e75b8d92b7262f

server/internal/webui/webui.go

@@ -0,0 +1,34 @@
+// Package webui embeds the production web dashboard build into the server
+// binary so a native install needs no nginx and no separate web container.
+//
+// The build pipeline copies web/dist into this package's dist/ directory
+// before `go build`. When that copy has not happened (plain `go build` from
+// a clean checkout), the embed holds only the .gitkeep placeholder and the
+// server runs API-only — Present() reports false and the caller logs it.
+package webui
+
+import (
+	"embed"
+	"io/fs"
+)
+
+//go:embed all:dist
+var distFS embed.FS
+
+// FS returns the embedded UI file tree rooted at the dist directory.
+func FS() (fs.FS, error) {
+	return fs.Sub(distFS, "dist")
+}
+
+// Present reports whether a real UI build is embedded (index.html exists),
+// as opposed to the empty placeholder tree from a UI-less build.
+func Present() bool {
+	sub, err := FS()
+	if err != nil {
+		return false
+	}
+	if _, err := fs.Stat(sub, "index.html"); err != nil {
+		return false
+	}
+	return true
+}