fix(stack): use fully qualified image references for Podman compatibility

stack/dedupe/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.12-alpine
+FROM docker.io/library/python:3.12-alpine
 
 # Needed to verify the CA chain when measuring each node's egress address
 # through its own CONNECT proxy.

stack/docker-compose.yml

@@ -37,7 +37,7 @@ services:
   # Seeds the engine's config into its named volume (bind-mounting that
   # path breaks startup, so it is copied instead).
   config-init:
-    image: busybox:1.36
+    image: docker.io/library/busybox:1.36
     command: ["sh", "-c", "install -o 1000 -g 1000 -m 0644 /seed.json /vol/config.json"]
     volumes:
       - ./config.json:/seed.json:ro

stack/generate-compose.py

@@ -79,7 +79,7 @@ def compose(n_nodes: int, base_port: int, node_rotation: int) -> str:
     w("  # Seeds the engine's config into its named volume (bind-mounting that")
     w("  # path breaks startup, so it is copied instead).")
     w("  config-init:")
-    w("    image: busybox:1.36")
+    w("    image: docker.io/library/busybox:1.36")
     w("    command: [\"sh\", \"-c\", \"install -o 1000 -g 1000 -m 0644 /seed.json /vol/config.json\"]")
     w("    volumes:")
     w("      - ./config.json:/seed.json:ro")

stack/tinyproxy/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM docker.io/library/alpine:3.20
 
 RUN apk add --no-cache tinyproxy
 

stack/warp/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:22.04
+FROM docker.io/library/ubuntu:22.04
 
 ENV DEBIAN_FRONTEND=noninteractive
 ENV WARP_LOG_LEVEL=info