feat(platform): add node orchestration and the felis entrypoint

The platform package that places servers across nodes and wires the operator, build, restore, and reaper subsystems, plus cmd/felis, the single binary that runs them.

cmd/felis/main.go

@@ -0,0 +1,13 @@
+// Command felis is the single multi-call binary for the platform (spec §25):
+// it dispatches to the api, operator, migrate, reaper, and apply subcommands.
+// Building one binary keeps the shared packages (scheme, store, config) linked
+// once and shipped in a single image.
+package main
+
+import (
+	"os"
+)
+
+func main() {
+	os.Exit(run(os.Args[1:], os.Stdout, os.Stderr))
+}