refactor: remove test.yaml workflow

Simplified CI/CD to two workflows:
- staging.yaml: Deploys to Dokku on main push (no tests)
- production.yaml: Full test suite + deploy on production push

Main branch deploys immediately to staging for fast iteration.
Production branch has comprehensive test gates before deployment.

.forgejo/workflows/test.yaml

@@ -1,84 +0,0 @@
-name: Tests
-
-on:
-  push:
-    branches:
-      - main
-  pull_request:
-    branches:
-      - main
-      - production
-
-env:
-  MIX_ENV: test
-
-jobs:
-  test-exunit:
-    name: ExUnit Tests
-    runs-on: ubuntu-latest
-
-    services:
-      postgres:
-        image: timescale/timescaledb:latest-pg16
-        env:
-          POSTGRES_USER: postgres
-          POSTGRES_PASSWORD: postgres
-          POSTGRES_DB: towerops_test
-        options: >-
-          --health-cmd pg_isready
-          --health-interval 10s
-          --health-timeout 5s
-          --health-retries 5
-
-    steps:
-      - name: Checkout code
-        uses: https://github.com/actions/checkout@v4
-
-      - name: Set up Elixir
-        uses: https://github.com/erlef/setup-beam@v1
-        with:
-          version-type: strict
-          elixir-version: '1.18.1'
-          otp-version: '27.2'
-
-      - name: Cache deps
-        uses: https://github.com/actions/cache@v4
-        with:
-          path: deps
-          key: ${{ runner.os }}-deps-${{ hashFiles('mix.lock') }}
-          restore-keys: ${{ runner.os }}-deps-
-
-      - name: Cache _build
-        uses: https://github.com/actions/cache@v4
-        with:
-          path: _build
-          key: ${{ runner.os }}-build-${{ hashFiles('lib/**/*.ex') }}-${{ hashFiles('mix.lock') }}
-          restore-keys: ${{ runner.os }}-build-
-
-      - name: Install system dependencies
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y openssl libssl1.1 libssl-dev libsnmp-dev snmp-mibs-downloader postgresql-client
-
-      - name: Install dependencies
-        run: mix deps.get
-
-      - name: Check formatting
-        run: mix format --check-formatted
-
-      - name: Compile (warnings as errors)
-        run: mix compile --warnings-as-errors
-
-      - name: Run tests with coverage
-        run: mix test --cover
-
-      - name: Run Credo
-        run: mix credo --strict
-
-      - name: Upload coverage reports
-        if: always()
-        uses: https://github.com/actions/upload-artifact@v4
-        with:
-          name: coverage-report
-          path: cover/
-          retention-days: 7