ci(P1-1): 删除重复的 tests.yml 流水线

ci-cd.yml 的 validate job 已经覆盖了 tests.yml 的全部功能：
- 单元测试 + 集成测试
- Black 代码格式化检查
- Flake8 静态分析
- 还有安全扫描、迁移检查等 tests.yml 没有的检查

且 ci-cd.yml 已配置 pull_request 触发，PR 时会自动运行。
删除重复流水线，减少维护成本。

.gitea/workflows/tests.yml

@@ -1,163 +0,0 @@
-name: Tests
-
-on:
-  pull_request:
-    branches: [ main ]
-
-jobs:
-  test:
-    runs-on: runtime-builder
-
-    steps:
-    - name: Checkout code
-      shell: sh
-      run: |
-        set -eu
-        python - <<'PY'
-        import io
-        import os
-        import tarfile
-        import time
-        import urllib.error
-        import urllib.request
-
-        url = f"{os.environ['GITHUB_API_URL']}/repos/{os.environ['GITHUB_REPOSITORY']}/archive/{os.environ['GITHUB_SHA']}.tar.gz"
-        request = urllib.request.Request(url, headers={"Authorization": f"token {os.environ['GITHUB_TOKEN']}"})
-        # Retry up to 5 times with backoff for transient 5xx errors
-        last_err = None
-        for attempt in range(5):
-            try:
-                with urllib.request.urlopen(request, timeout=120) as response:
-                    archive = response.read()
-                break
-            except urllib.error.HTTPError as e:
-                last_err = e
-                if e.code >= 500 and attempt < 4:
-                    wait = 2 ** attempt
-                    print(f"Checkout HTTP {e.code}, retrying in {wait}s (attempt {attempt+1}/5)...")
-                    time.sleep(wait)
-                    continue
-                raise
-            except Exception as e:
-                last_err = e
-                if attempt < 4:
-                    wait = 2 ** attempt
-                    print(f"Checkout error: {e}, retrying in {wait}s (attempt {attempt+1}/5)...")
-                    time.sleep(wait)
-                    continue
-                raise
-        else:
-            raise last_err
-
-        with tarfile.open(fileobj=io.BytesIO(archive), mode='r:gz') as tar:
-            root_prefix = tar.getmembers()[0].name.split('/', 1)[0] + '/'
-            for member in tar.getmembers():
-                name = member.name
-                if name == root_prefix[:-1]:
-                    continue
-                if name.startswith(root_prefix):
-                    member.name = name[len(root_prefix):]
-                if member.name:
-                    tar.extract(member, '.')
-        PY
-
-    - name: Show Python version
-      shell: sh
-      run: |
-        set -eu
-        python --version
-        python -m pip --version
-
-    - name: Install dependencies
-      shell: sh
-      run: |
-        set -eu
-        python -m pip install --upgrade pip -i https://mirrors.aliyun.com/pypi/simple/ --trusted-host mirrors.aliyun.com
-        python -m pip install -r requirements.txt -r requirements-dev.txt -i https://mirrors.aliyun.com/pypi/simple/ --trusted-host mirrors.aliyun.com
-
-    - name: Run unit tests
-      shell: sh
-      run: |
-        set -eu
-        PYTHONPATH="$PWD/apps/api:$PWD" python -m pytest tests/unit -q
-
-    - name: Run integration tests
-      shell: sh
-      run: |
-        set -eu
-        PYTHONPATH="$PWD/apps/api:$PWD" python -m pytest tests/integration -q --timeout=60 -x
-
-  lint:
-    runs-on: runtime-builder
-
-    steps:
-    - name: Checkout code
-      shell: sh
-      run: |
-        set -eu
-        python - <<'PY'
-        import io
-        import os
-        import tarfile
-        import time
-        import urllib.error
-        import urllib.request
-
-        url = f"{os.environ['GITHUB_API_URL']}/repos/{os.environ['GITHUB_REPOSITORY']}/archive/{os.environ['GITHUB_SHA']}.tar.gz"
-        request = urllib.request.Request(url, headers={"Authorization": f"token {os.environ['GITHUB_TOKEN']}"})
-        # Retry up to 5 times with backoff for transient 5xx errors
-        last_err = None
-        for attempt in range(5):
-            try:
-                with urllib.request.urlopen(request, timeout=120) as response:
-                    archive = response.read()
-                break
-            except urllib.error.HTTPError as e:
-                last_err = e
-                if e.code >= 500 and attempt < 4:
-                    wait = 2 ** attempt
-                    print(f"Checkout HTTP {e.code}, retrying in {wait}s (attempt {attempt+1}/5)...")
-                    time.sleep(wait)
-                    continue
-                raise
-            except Exception as e:
-                last_err = e
-                if attempt < 4:
-                    wait = 2 ** attempt
-                    print(f"Checkout error: {e}, retrying in {wait}s (attempt {attempt+1}/5)...")
-                    time.sleep(wait)
-                    continue
-                raise
-        else:
-            raise last_err
-
-        with tarfile.open(fileobj=io.BytesIO(archive), mode='r:gz') as tar:
-            root_prefix = tar.getmembers()[0].name.split('/', 1)[0] + '/'
-            for member in tar.getmembers():
-                name = member.name
-                if name == root_prefix[:-1]:
-                    continue
-                if name.startswith(root_prefix):
-                    member.name = name[len(root_prefix):]
-                if member.name:
-                    tar.extract(member, '.')
-        PY
-
-    - name: Install dependencies
-      shell: sh
-      run: |
-        set -eu
-        python -m pip install --upgrade pip -i https://mirrors.aliyun.com/pypi/simple/ --trusted-host mirrors.aliyun.com
-        python -m pip install -r requirements.txt -r requirements-dev.txt -i https://mirrors.aliyun.com/pypi/simple/ --trusted-host mirrors.aliyun.com
-
-    - name: Run Black (check only)
-      shell: sh
-      run: |
-        set -eu
-        python -m black --check alembic apps packages tests scripts
-
-    - name: Run Flake8
-      shell: sh
-      run: |
-        set -eu
-        python -m flake8 apps packages tests --count --statistics