Add healthcheck and attempt to fix devcontainer

user was root instead of vscode, and pi was broken.
Claude code had gone missing

.devcontainer/devcontainer.json

@@ -3,10 +3,9 @@
     "dockerComposeFile": "docker-compose.yml",
     "service": "app",
     "workspaceFolder": "/workspaces/firehose",
-    "remoteUser": "root",
+    "remoteUser": "vscode",
     "containerEnv": {
-        "DB_HOST": "db",
-        "HOME": "/home/vscode"
+        "DB_HOST": "db"
     },
     "features": {
         "ghcr.io/devcontainers/features/python:1": {},
@@ -20,7 +19,7 @@
         "source=${localEnv:HOME}/.pi/agent/bin,target=/home/vscode/.pi/agent/bin,type=bind,consistency=cached"
     ],
     "postCreateCommand": {
-        "pi-subagents": "bash -ic 'pi install npm:pi-subagents'"
+        "pi-subagents-disabled": "echo 'pi-subagents disabled: upstream JSON schema bug — investigate version pinning separately'"
     },
     "customizations": {
         "jetbrains": {