CUB-CI: Remove redundant build-dev.yaml — dev.yml already handles this

build-dev.yaml uses actions/setup-go@v5 and actions/setup-node@v4 which
are incompatible with Gitea Act runner (no node20 runtime). dev.yml is
the canonical build workflow; having two competing workflows on the same
triggers was causing duplicate CI runs and misleading failures.

.gitea/workflows/build-dev.yaml

@@ -1,85 +0,0 @@
-name: Build (Dev)
-
-on:
-  push:
-    branches: [dev]
-  pull_request:
-    branches: [dev]
-  workflow_dispatch:
-
-env:
-  GO_VERSION: "1.23"
-  NODE_VERSION: "22"
-  BINARY_NAME: server
-
-jobs:
-  build-go-backend:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Setup Go
-        uses: actions/setup-go@v5
-        with:
-          go-version: ${{ env.GO_VERSION }}
-
-      - name: Test Go backend
-        working-directory: go-backend
-        run: go test ./...
-
-      - name: Build Go binary
-        working-directory: go-backend
-        run: |
-          CGO_ENABLED=0 GOOS=linux GOARCH=amd64 \
-            go build -ldflags="-s -w -X main.version=${GITHUB_SHA:0:8}" \
-            -o ${{ env.BINARY_NAME }} ./cmd/server
-
-      - name: Upload Go binary
-        uses: actions/upload-artifact@v4
-        with:
-          name: go-backend-binary
-          path: go-backend/${{ env.BINARY_NAME }}
-          retention-days: 3
-
-  build-frontend:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Setup Node
-        uses: actions/setup-node@v4
-        with:
-          node-version: ${{ env.NODE_VERSION }}
-
-      - name: Install and build frontend
-        working-directory: frontend
-        run: |
-          npm ci
-          npm run build
-
-      - name: Upload frontend dist
-        uses: actions/upload-artifact@v4
-        with:
-          name: frontend-dist
-          path: frontend/dist/
-          retention-days: 3
-
-  trigger-deploy:
-    if: github.event_name == 'push'
-    needs: [build-go-backend, build-frontend]
-    runs-on: ubuntu-latest
-    steps:
-      - name: Trigger deploy workflow
-        uses: actions/github-script@v7
-        with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          script: |
-            await github.rest.repos.createDispatchEvent({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              event_type: 'dev-build-success',
-              client_payload: {
-                sha: context.sha,
-                ref: context.ref
-              }
-            })