ci: split CI by area with path filters and speed up releases

- ci.yml becomes ci-api, ci-contract, ci-recommender, ci-ts, ci-mobile and
  docker workflows, each filtered by paths; docs-only commits run nothing
- docker builds all four images in one job with plain docker build on the
  runner host, so the layer cache survives between runs
- release no longer re-runs the test suite (the tagged commit already passed
  CI on main); version and release notes are one job
- the android job mounts persistent Gradle and Android SDK caches from
  /opt/ci-cache (when the runner allows the volumes) and uses --build-cache
- RELEASE_TOKEN is optional: fall back to the built-in job token
- docs: CI layout and act_runner settings (capacity, cache, valid_volumes)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/ci-api.yml

@@ -0,0 +1,32 @@
+# Go: сервис api и storage-agent (docs/ci-cd.md). Только при изменении их кода или контракта.
+name: ci / api
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'services/api/**'
+      - 'api/openapi.yaml'
+      - '.gitea/workflows/ci-api.yml'
+  pull_request:
+    paths:
+      - 'services/api/**'
+      - 'api/openapi.yaml'
+      - '.gitea/workflows/ci-api.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  api:
+    runs-on: ubuntu-latest
+    defaults: { run: { working-directory: services/api } }
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with: { go-version: "1.24", cache-dependency-path: services/api/go.sum }
+      - run: test -z "$(gofmt -l .)" || (gofmt -l . && exit 1)
+      - run: go vet ./...
+      - run: go test -race -coverprofile=coverage.out ./...
+      - run: go build ./cmd/...