refactor: split services/docker.py into focused modules (Task 3.3)

- Create services/docker/compose.py — compose file generation and commands
- Create services/docker/container.py — container lifecycle and queries
- Create services/docker/config_staging.py — config folder file writing
- Create services/docker/tunnel.py — Cloudflare tunnel management
- Create services/docker/__init__.py — barrel exports
- Delete services/docker.py (replaced by package)
- All imports in api/tool_instances.py remain functional

Quality gates: Python syntax check (pass), imports verified
Refs: repo-restructure Task 3.3

apps/api/src/services/docker/container.py

@@ -0,0 +1,121 @@
+"""Docker container lifecycle and query operations."""
+
+import socket
+import subprocess
+
+
+def get_container_id(instance_name: str) -> str | None:
+    """Get the container ID for a compose service.
+
+    Args:
+        instance_name: The service name in compose
+
+    Returns:
+        Container ID or None if not found
+    """
+    result = subprocess.run(
+        ["docker", "ps", "-q", "--filter", f"name={instance_name}"],
+        capture_output=True,
+        text=True,
+    )
+
+    if result.returncode == 0 and result.stdout.strip():
+        return result.stdout.strip().split("\n")[0]
+    return None
+
+
+def get_container_name(instance_name: str) -> str | None:
+    """Get the full container name for a compose service.
+
+    Args:
+        instance_name: The service name in compose
+
+    Returns:
+        Container name or None if not found
+    """
+    result = subprocess.run(
+        ["docker", "ps", "--format", "{{.Names}}", "--filter", f"name={instance_name}"],
+        capture_output=True,
+        text=True,
+    )
+
+    if result.returncode == 0 and result.stdout.strip():
+        return result.stdout.strip().split("\n")[0]
+    return None
+
+
+def connect_container_to_network(container_name: str, network_name: str = "backend") -> bool:
+    """Connect a Docker container to an existing network.
+
+    Args:
+        container_name: Name or ID of the container
+        network_name: Name of the Docker network (default: backend)
+
+    Returns:
+        True if successful, False otherwise
+    """
+    result = subprocess.run(
+        ["docker", "network", "connect", network_name, container_name],
+        capture_output=True,
+        text=True,
+    )
+    return result.returncode == 0
+
+
+def get_container_status(container_id: str) -> str:
+    """Get the status of a Docker container.
+
+    Args:
+        container_id: Docker container ID
+
+    Returns:
+        Container status string (running, exited, etc.)
+    """
+    result = subprocess.run(
+        ["docker", "inspect", "-f", "{{.State.Status}}", container_id],
+        capture_output=True,
+        text=True,
+    )
+
+    if result.returncode == 0:
+        return result.stdout.strip()
+    return "unknown"
+
+
+def get_container_logs(container_id: str, tail: int = 100) -> str:
+    """Get the logs of a Docker container.
+
+    Args:
+        container_id: Docker container ID
+        tail: Number of lines to return
+
+    Returns:
+        Container logs
+    """
+    result = subprocess.run(
+        ["docker", "logs", "--tail", str(tail), container_id],
+        capture_output=True,
+        text=True,
+    )
+
+    if result.returncode == 0:
+        return result.stdout
+    return f"Failed to get logs: {result.stderr}"
+
+
+def find_free_port(start: int = 10000, end: int = 20000) -> int:
+    """Find a free TCP port in the given range.
+
+    Args:
+        start: Start of port range
+        end: End of port range
+
+    Returns:
+        Free port number
+    """
+    for port in range(start, end):
+        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+            if s.connect_ex(("localhost", port)) != 0:
+                return port
+
+    raise RuntimeError(f"No free port found in range {start}-{end}")