M0: repo scaffold, backend skeleton, schema + migrations, dev compose, docs

- Apache-2.0, README, CONTRIBUTING, CODE_OF_CONDUCT, SECURITY, issue templates
- FastAPI app with /api/v1 healthz/readyz/system-status (honest AI disclosure)
- Full SQLAlchemy schema (users, devices, refresh tokens, recordings, assets,
  upload sessions, transcripts, summaries, tags, jobs, exports) + Alembic
  migrations incl. Postgres FTS tsvector columns
- Settings via SHONAR_* env only; local + S3 storage abstraction with
  path-traversal-safe keys
- Docker dev compose (postgres+redis, 127.0.0.1-only); CI workflow; scripts
- shared/openapi.json contract generated from app

.github/workflows/ci.yml

@@ -0,0 +1,49 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  backend:
+    runs-on: ubuntu-latest
+    services:
+      postgres:
+        image: postgres:16-alpine
+        env:
+          POSTGRES_USER: shonar
+          POSTGRES_PASSWORD: shonar
+          POSTGRES_DB: shonar_test
+        ports: ["5432:5432"]
+        options: >-
+          --health-cmd "pg_isready -U shonar"
+          --health-interval 5s --health-timeout 3s --health-retries 10
+    defaults:
+      run:
+        working-directory: backend
+    steps:
+      - uses: actions/checkout@v4
+      - uses: astral-sh/setup-uv@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+      - run: uv venv .venv && uv pip install -e ".[dev]"
+      - run: .venv/bin/ruff check .
+      - run: .venv/bin/pytest
+        env:
+          SHONAR_TEST_DATABASE_URL: postgresql+asyncpg://shonar:shonar@localhost:5432/shonar_test
+
+  android:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: android
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with: { distribution: temurin, java-version: 17 }
+      - uses: gradle/actions/setup-gradle@v4
+      # Skipped until the Android project lands (M3).
+      - run: ./gradlew test assembleDebug --no-daemon
+        continue-on-error: ${{ !hashFiles('android/**/build.gradle.kts') }}