Add BaseDeviceConnector and DeviceConnectorProtocol for standardized device connector patterns

[Copilot]

Phase 1 of device connector refactoring (#2). Adds foundation classes for standardizing configuration loading, logging, error handling, and serial logger management across 16+ device connectors without breaking existing implementations.

Changes

New Base Classes

• DeviceConnectorProtocol: Runtime-checkable Protocol (PEP 544) defining the device connector interface for type checking
• BaseDeviceConnector: Base class providing:
  • load_config(path) / load_job_data(path) - Standardized YAML/JSON loading
  • run_phase(name, func, *args, **kwargs) - Consistent BEGIN/END logging and error handling
  • create_serial_logger(config, filename) - Unified serial logger lifecycle
  • get_provision_data() / get_test_data() / get_test_username() - Safe data extraction

Usage Pattern

from testflinger_device_connectors.devices import DefaultDevice
from testflinger_device_connectors.devices.base import BaseDeviceConnector

class DeviceConnector(BaseDeviceConnector, DefaultDevice):
    def provision(self, args):
        config = self.load_config(args.config)
        job_data = self.load_job_data(args.job_data)
        return self.run_phase("provision", self._do_provision, config, job_data)
    
    def _do_provision(self, config, job_data):
        image_url = self.get_provision_data(job_data, "image_url")
        # provisioning logic
        return 0

Documentation

• docs/NEW_BASE_CLASSES.md - API reference, usage patterns, migration guide
• docs/EXAMPLES.md - Three implementation patterns with error handling examples

Testing

• 30 new tests covering protocol validation, config/data loading, phase execution, error handling, and helper methods
• All 139 tests passing (109 existing + 30 new)

Design

Non-breaking: Existing DefaultDevice unchanged, all current connectors work without modification. New classes are additive and optional, enabling incremental adoption in future phases.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• astral.sh
  • Triggering command: curl -LsSf REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

can you please take a look at #2 issue and take care of the first item: Phase 1: Add New Base Classes (Non-Breaking)

Created from VS Code via the GitHub Pull Request extension.

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