devcontainer: use dynamic host ports so worktrees don't collide

Publish container ports without a fixed host side in the backend and
asset_list compose files, and switch forwardPorts to service-qualified
form. Lets a second worktree's devcontainer spin up without conflicting
on host 8000/5432 (backend) or 8081 (asset_list), matching the pattern
in assessment-model-sales-frontend.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.devcontainer/asset_list/devcontainer.json

@@ -9,7 +9,7 @@
     // Optional, just makes getting from Downloads (local env) easier
     "source=${localEnv:HOME},target=/home/vscode,type=bind"
   ],
-  "forwardPorts": [8081],
+  "forwardPorts": ["model-sal:8080"],
   "customizations": {
     "vscode": {
       "extensions": [

.devcontainer/asset_list/docker-compose.yml

@@ -12,7 +12,10 @@ services:
     networks:
       - model-net
     ports:
-      - "8081:8080"
+      # Host port left unspecified so Docker assigns a free one — lets multiple
+      # worktrees of this repo run at once without colliding. VS Code's
+      # forwardPorts (in devcontainer.json) forwards container :8080 to your machine.
+      - "8080"
 
 networks:
   model-net:

.devcontainer/backend/devcontainer.json

@@ -42,9 +42,9 @@
   "containerEnv": {
     "PYTHONFLAGS": "-Xfrozen_modules=off"
   },
-  "forwardPorts": [8000],
+  "forwardPorts": ["model-backend:8000"],
   "portsAttributes": {
-    "8000": {
+    "model-backend:8000": {
       "label": "FastAPI",
       "onAutoForward": "notify"
     }

.devcontainer/backend/docker-compose.yml

@@ -10,7 +10,10 @@ services:
         USER_GID: ${GID:-1000}
     command: sleep infinity
     ports:
-      - "8000:8000"
+      # Host port left unspecified so Docker assigns a free one — lets multiple
+      # worktrees of this repo run at once without colliding. VS Code's
+      # forwardPorts (in devcontainer.json) forwards container :8000 to your machine.
+      - "8000"
     volumes:
       - ../../:/workspaces/model
       - ~/.gitconfig:/home/vscode/.gitconfig:ro
@@ -30,7 +33,10 @@ services:
     image: postgres:17.4
     restart: unless-stopped
     ports:
-      - 5432:5432
+      # Dynamic host port (see model-backend above) so a second worktree's db
+      # doesn't collide on 5432. Reach it from inside the container via host
+      # "db:5432"; from your machine, use the forwarded port VS Code reports.
+      - "5432"
     environment:
       - PGDATABASE=tech_team_local_db
       - POSTGRES_USER=postgres