## MODIFIED Requirements

### Requirement: Base HTTP client
The system SHALL provide a base HTTP client that sends requests to the Planka API. The client SHALL construct URLs by joining the configured base URL with the API path. The client SHALL attach an `x-api-key: <key>` header to every request. The client SHALL send and receive JSON (`Content-Type: application/json`). The client SHALL accept a `*slog.Logger` and log every request at DEBUG level with method, path, status code, and duration. The client SHALL log errors at WARN level.

#### Scenario: Successful API request
- **WHEN** the client sends a request to a valid endpoint
- **THEN** the response body SHALL be returned as parsed JSON
- **AND** the request SHALL include the `x-api-key` header
- **AND** a DEBUG log entry SHALL be emitted with method, path, status, and duration

#### Scenario: API returns error status
- **WHEN** the API responds with a 4xx or 5xx status code
- **THEN** the client SHALL return an `APIError` containing the HTTP status code and response message
- **AND** a WARN log entry SHALL be emitted

#### Scenario: Network failure
- **WHEN** the HTTP request fails due to a network error (connection refused, timeout, DNS failure)
- **THEN** the client SHALL return a Go error wrapping the underlying network error

### Requirement: Authentication from environment
The system SHALL read `PLANKA_URL` from the environment to determine the API base URL. The system SHALL read `PLANKA_API_KEY` from the environment to determine the API key. Global flags `--url` and `--api-key` SHALL override the corresponding environment variables. Flag values SHALL take precedence over environment variables.

#### Scenario: Auth from environment variables
- **WHEN** `PLANKA_URL` and `PLANKA_API_KEY` are set in the environment
- **AND** no `--url` or `--api-key` flags are provided
- **THEN** the client SHALL use the environment variable values

#### Scenario: Flag overrides environment
- **WHEN** `--url` or `--api-key` flags are provided
- **THEN** the flag values SHALL take precedence over environment variables

#### Scenario: Missing configuration
- **WHEN** neither the environment variable nor the flag is set for URL or API key
- **THEN** the system SHALL print an error message and exit with code 1