docs(path-b): mark weeks 1-3 shipped; preview routing scoped

- AI_PATH_B_EXECUTION_PLAN.md: Status changed from "proposed" to
  "week 1 shipped", weeks 1-3 checkboxes flipped to ✅ for the parts
  that landed in vibn-frontend@4ba9407 and @41d4d37. Lists what's
  still manual (DNS wildcard, Coolify host image build, Traefik cert).
- vibn-dev/PREVIEWS.md: Architecture for *.preview.vibnai.com
  routing, the deferred Coolify-compose-hot-update piece, and an
  HMR/websocket troubleshooting checklist.
- vibn-dev/setup-on-coolify.sh: One-shot script to build
  vibn-dev:latest on the Coolify host (referenced by the compose
  template's pull_policy: never).

Made-with: Cursor

vibn-dev/setup-on-coolify.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+# Build the vibn-dev image on the Coolify host so every project's
+# docker-compose can reference `vibn-dev:latest` with pull_policy: never.
+#
+# Run this ONCE per Coolify host before the first chat session uses
+# Path B. Re-run whenever you bump the Dockerfile.
+#
+# Usage (from a workstation):
+#   scp -r vibn-dev/ root@<coolify-host>:/tmp/
+#   ssh root@<coolify-host> 'bash /tmp/vibn-dev/setup-on-coolify.sh'
+#
+# Or run via the Coolify SSH backbone (vibn-logs user has docker access):
+#   ssh -i ~/.ssh/coolify_logs vibn-logs@<host> \
+#     "cd /tmp/vibn-dev && docker build -t vibn-dev:latest ."
+
+set -euo pipefail
+
+cd "$(dirname "$0")"
+
+echo "Building vibn-dev:latest on $(hostname)..."
+docker build -t vibn-dev:latest .
+
+echo
+echo "Done. Image:"
+docker images vibn-dev:latest --format 'table {{.Repository}}:{{.Tag}}\t{{.Size}}\t{{.CreatedSince}}'
+
+echo
+echo "Smoke test (should print 'ok'):"
+docker run --rm vibn-dev:latest bash -c 'rg --version > /dev/null && git --version > /dev/null && echo ok'
+
+echo
+echo "vibn-dev is ready. New AI dev containers will reference this image"
+echo "via 'image: vibn-dev:latest' + 'pull_policy: never' in their compose."