ci: merge deploy into ci.yaml to fix orphaned-job race

Both ci.yaml and deploy-gke.yaml triggered on push/main and shared the
neuron-runner concurrency group. Gitea's cancel-in-progress:false protects
running jobs but not queued ones — a new push arriving while a build was
in progress cancelled the queued deploy job from the previous push, leaving
the soul permanently at 0/0 replicas on GKE.

Fix: add deploy as a needs:build job in ci.yaml so build+deploy are a single
workflow instance. One push queues one instance — no more orphaned deploys.
deploy-gke.yaml is demoted to workflow_dispatch-only for manual slot overrides.

.gitea/workflows/deploy-gke.yaml

@@ -1,16 +1,13 @@
-name: Deploy Soul to GKE
+name: Deploy Soul to GKE (manual)
 
-# Triggers on push to main — after the soul binary is built and published
-# by ci.yaml, this workflow builds the Docker image and blue-green deploys
-# to the neuron-prod namespace on GKE.
+# MANUAL OVERRIDE ONLY — push-triggered deploys now run as the 'deploy' job
+# in ci.yaml (needs: build), which eliminates the two-workflow concurrency
+# race that was cancelling queued deploy runs.
 #
-# This workflow runs AFTER ci.yaml has published the neuron-soul generic
-# artifact to Artifact Registry. The Docker build downloads that binary.
+# Use this workflow only when you need to deploy a specific slot manually
+# (e.g. rollback, force a slot override) without triggering a full CI build.
 
 on:
-  push:
-    branches:
-      - main
   workflow_dispatch:
     inputs:
       slot:
@@ -18,8 +15,7 @@ on:
         required: false
         default: "green"
 
-# Serialize all builds on this runner — concurrent jobs exhaust the Docker daemon.
-# A queued deploy runs after the in-progress build finishes.
+# Manual deploys still share the runner serialization group.
 concurrency:
   group: neuron-runner
   cancel-in-progress: false