copytrade.py moves out of archive/ + Fly health check (watchdog layer 1)

The execution engine was load-bearing from archive/ — the one thing in
there that wasn't retired. Now at repo root next to copybot.py; the two
archived scripts that imported it as a sibling get a parent-path shim.
fly.toml gains an http /health check so Fly restarts a dark machine
(self-heal); the notify half is the GH Actions watchdog (next commit).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

fly.toml

@@ -23,3 +23,15 @@ primary_region = "arn"
 [[vm]]
   size = "shared-cpu-1x"
   memory = "512mb"
+
+# health check: Fly restarts the machine if /health stops answering — the
+# self-heal half of the watchdog (the notify half is the GitHub Actions
+# watchdog workflow -> Discord). grace covers the boot clone.
+[checks]
+  [checks.health]
+    type = "http"
+    port = 8080
+    path = "/health"
+    interval = "30s"
+    timeout = "5s"
+    grace_period = "60s"