BREAKING: Remove constructor callbacks in favor of event emitter pattern

[eman]

Summary

This PR removes the duplicate callback parameters from the NavienMqttClient constructor and standardizes on the event emitter pattern for all client events.

Breaking Changes

Removed constructor parameters:

• on_connection_interrupted
• on_connection_resumed

Migration:

# OLD (removed in v6.0.0)
mqtt_client = NavienMqttClient(
    auth_client,
    on_connection_interrupted=on_interrupted,
    on_connection_resumed=on_resumed,
)

# NEW (use event emitter pattern)
mqtt_client = NavienMqttClient(auth_client)
mqtt_client.on('connection_interrupted', on_interrupted)
mqtt_client.on('connection_resumed', on_resumed)

Benefits

1. Multiple listeners per event - Not limited to one callback
2. Consistent API - Same pattern as temperature_changed, mode_changed, etc.
3. Dynamic management - Add/remove listeners at runtime with .on() and .off()
4. Async support - Event handlers can be async functions
5. Priority-based execution - Control order of handler execution
6. Cleaner code - Separation of client creation and event registration

Changes

Code Changes

• src/nwp500/mqtt_client.py (-25 lines)
  • Removed constructor callback parameters
  • Removed callback storage and invocation logic
  • Simplified constructor signature

Example Updates

• examples/command_queue_demo.py - Updated to use event emitter
• examples/reconnection_demo.py - Updated to use event emitter
• examples/event_emitter_demo.py - Already using correct pattern ✓

Documentation Updates

• docs/python_api/mqtt_client.rst - Updated API docs and examples
• .github/copilot-instructions.md - Added backward compatibility policy
• CHANGELOG.rst - Added v6.0.0 entry with migration guide

Validation

✅ Type checking: No errors
✅ Linting: All checks passed
✅ Syntax: All files compile successfully
✅ References: No remaining old pattern usage

Version Impact

This requires a major version bump (v5.0.2 → v6.0.0) due to breaking API changes.

Rationale

The library is young with no external clients. This change eliminates duplicate functionality and establishes a single, consistent pattern for event handling across the entire API.

[Copilot]

Pull Request Overview

This PR removes duplicate callback parameters from the NavienMqttClient constructor, standardizing on the event emitter pattern for all connection events. This is a breaking change that simplifies the API by eliminating redundant functionality and establishing a consistent event-driven architecture.

Key Changes:

• Removed on_connection_interrupted and on_connection_resumed constructor parameters
• Standardized all examples to use the .on() event emitter pattern
• Cleaned up backward compatibility exception re-exports from api_client and auth modules
• Updated documentation to reflect the new event-only approach

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/nwp500/mqtt_client.py	Removed constructor callback parameters and internal callback invocation logic
src/nwp500/auth.py	Removed backward compatibility exception re-exports from __all__
src/nwp500/api_client.py	Removed backward compatibility exception re-exports and simplified imports
tests/test_auth.py	Updated imports to use exceptions module
examples/reconnection_demo.py	Migrated from constructor callbacks to event emitter pattern
examples/command_queue_demo.py	Migrated from constructor callbacks to event emitter pattern
examples/test_api_client.py	Updated imports to use exceptions module
examples/device_status_callback_debug.py	Updated imports to use exceptions module
examples/device_status_callback.py	Updated imports to use exceptions module
examples/device_feature_callback.py	Updated imports to use exceptions module
docs/python_api/mqtt_client.rst	Updated API documentation and examples to show event emitter pattern
CHANGELOG.rst	Added v6.0.0 entry with breaking changes documentation and migration guide
.github/copilot-instructions.md	Added backward compatibility policy and enhanced validation requirements

[Copilot]

[nitpick] The comment spans lines 179-181, but the actual implementation detail being explained is only on line 182. The comment should be condensed to a single line or reformatted to be more concise since it's explaining a simple state tracking variable.

Suggested change

	# Connection state tracking
	# Note: Simpler to check than _connection_manager.is_connected
	# (which can be None before connect())
	# Tracks the current MQTT connection (simpler to check than _connection_manager.is_connected, which can be None before connect())