feat(plugins): entry-point plugin architecture for tasks and agents (#59)

[trixy-the-ai-bot]

Summary

Implements the plugin architecture described in #59 using Python's importlib.metadata entry points.

• loony_dev/plugins/base.py — TaskPlugin and AgentPlugin ABCs plus PluginConflictError
• loony_dev/plugins/loader.py — discovers plugins from entry point groups loony_dev.task_plugins and loony_dev.agent_plugins; isolates per-plugin load failures; raises loudly on name or task-type conflicts
• loony_dev/tasks/plugins.py — GithubTaskPlugin wrapping all six built-in task classes
• loony_dev/agents/plugins.py — ClaudeAgentPlugin wrapping NullAgent, CodingAgent, PlanningAgent
• orchestrator.py — Orchestrator now accepts an injected task_classes list; hard-coded TASK_CLASSES removed
• cli.py — worker command calls load_task_plugins() / load_agent_plugins() instead of hard-coded lists
• pyproject.toml — registers built-in github and claude plugins under the new entry point groups

Plugin authoring workflow

1. Create a package with pyproject.toml declaring the entry point group
2. Subclass Task/Agent from loony_dev
3. Wrap in TaskPlugin or AgentPlugin
4. uv pip install -e . — the loony-dev worker command auto-discovers it

For iteration without reinstalling: set LOONY_DEV_EXTRA_PLUGINS=module:ClassName.

Test plan

• load_task_plugins() returns all six built-in task classes in priority order
• load_agent_plugins() returns NullAgent, CodingAgent, PlanningAgent
• TaskPlugin and AgentPlugin ABCs enforce name and primary method as abstract
• PluginConflictError is an Exception subclass
• uv pip install -e . registers entry points; verified with live importlib.metadata.entry_points()

Closes #59

🤖 Generated with Claude Code

[trixy-the-ai-bot]

Merge conflicts resolved.

A merge conflict in loony_dev/cli.py was resolved by combining changes from two branches: the detect_default_branch() logic and default_branch parameter from PR #85 (main), and the dynamic load_task_plugins() / load_agent_plugins() calls from the plugin branch. The resolved merge commit was pushed to feat/plugin-architecture-59.

[trixy-the-ai-bot]

Merge conflicts resolved.

The merge conflict in loony_dev/orchestrator.py was resolved by reconciling two diverging import strategies. The branch's plugin architecture removes direct task class imports in favor of injected task_classes, while main had added new direct imports including RateLimitedError. The resolution kept RateLimitedError (still needed in dispatch()) and dropped the direct task class imports, with the merge commit pushed to feat/plugin-architecture-59.