chore: remove dead core/parmanode crate

The parmanode compatibility layer was scaffolded but never wired up —
zero imports or calls from anywhere in the codebase. Closes gitea#1.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/Cargo.toml

@@ -4,7 +4,6 @@ resolver = "2"
 members = [
     "archipelago",
     "container",
-    "parmanode",
     "performance",
     "security",
 ]