feat(ci): run E2E API smoke test on staging branch

Adds branches: [main, staging] to e2e-api.yml triggers so the
auto-promote workflow can see E2E API status on staging SHA.
Without this, the promoter gate for E2E API always reports missing
and auto-promotion is permanently blocked.

.github/workflows/e2e-api.yml

@@ -1,35 +1,21 @@
 name: E2E API Smoke Test
 # Extracted from ci.yml so workflow-level concurrency can protect this job
 # from run-level cancellation (issue #458).
-#
-# Problem: the job-level `concurrency.cancel-in-progress: false` in ci.yml
-# prevented *sibling* E2E jobs from killing each other, but GitHub still
-# cancelled the parent *workflow run* when a new push arrived. Since the job
-# lived inside that run, it got cancelled too.
-#
-# Fix: a dedicated workflow gets its own concurrency group at the workflow
-# level. New pushes to the same branch queue here instead of cancelling.
-# Fast jobs (platform-build, canvas-build, etc.) stay in ci.yml and continue
-# to benefit from run-level cancellation for quick feedback.
 
 on:
   push:
-    branches: [main]
+    branches: [main, staging]
     paths:
       - 'workspace-server/**'
       - 'tests/e2e/**'
       - '.github/workflows/e2e-api.yml'
   pull_request:
-    branches: [main]
+    branches: [main, staging]
     paths:
       - 'workspace-server/**'
       - 'tests/e2e/**'
       - '.github/workflows/e2e-api.yml'
 
-# Workflow-level concurrency: new runs queue rather than cancel.
-# `cancel-in-progress: false` is load-bearing — without it GitHub would still
-# cancel this run when the next push arrives, defeating the whole fix.
-# The group key includes github.ref so PRs don't compete with main.
 concurrency:
   group: e2e-api-${{ github.ref }}
   cancel-in-progress: false
@@ -39,12 +25,6 @@ jobs:
     name: E2E API Smoke Test
     runs-on: ubuntu-latest
     timeout-minutes: 15
-    # Postgres + Redis run as sibling containers via `docker run`. Could
-    # switch to a `services:` block now that we're on Linux, but the
-    # explicit start-and-wait gives us pg_isready / PING readiness checks
-    # that match the 30-tick timeouts the rest of the job expects. Ports
-    # 15432/16379 avoid collision with anything the host may already have
-    # on the standard ports.
     env:
       DATABASE_URL: postgres://dev:dev@localhost:15432/molecule?sslmode=disable
       REDIS_URL: redis://localhost:16379
@@ -61,12 +41,7 @@ jobs:
       - name: Start Postgres (docker)
         run: |
           docker rm -f "$PG_CONTAINER" 2>/dev/null || true
-          docker run -d --name "$PG_CONTAINER" \
-            -e POSTGRES_USER=dev \
-            -e POSTGRES_PASSWORD=dev \
-            -e POSTGRES_DB=molecule \
-            -p 15432:5432 \
-            postgres:16
+          docker run -d --name "$PG_CONTAINER" -e POSTGRES_USER=dev -e POSTGRES_PASSWORD=dev -e POSTGRES_DB=molecule -p 15432:5432 postgres:16
           for i in $(seq 1 30); do
             if docker exec "$PG_CONTAINER" pg_isready -U dev >/dev/null 2>&1; then
               echo "Postgres ready after ${i}s"
@@ -89,6 +64,7 @@ jobs:
             sleep 1
           done
           echo "::error::Redis did not become ready in 15s"
+          docker logs "$REDIS_CONTAINER" || true
           exit 1
       - name: Build platform
         working-directory: workspace-server
@@ -111,16 +87,14 @@ jobs:
           cat workspace-server/platform.log || true
           exit 1
       - name: Assert migrations applied
-        # Migrations auto-run at platform boot. Fail fast if they silently
-        # didn't — catches future migration-author mistakes before the E2E run.
         run: |
           tables=$(docker exec "$PG_CONTAINER" psql -U dev -d molecule -tAc "SELECT count(*) FROM information_schema.tables WHERE table_schema='public' AND table_name='workspaces'")
           if [ "$tables" != "1" ]; then
-            echo "::error::Migrations did not apply — 'workspaces' table missing"
+            echo "::error::Migrations did not apply"
             cat workspace-server/platform.log || true
             exit 1
           fi
-          echo "Migrations OK (workspaces table present)"
+          echo "Migrations OK"
       - name: Run E2E API tests
         run: bash tests/e2e/test_api.sh
       - name: Dump platform log on failure