feat(poe): add rtk poe subcommand for filtered poe task execution

[polfeliu]

Summary

• New rtk poe <task> subcommand that resolves poe tasks from pyproject.toml and runs each sub-command through the appropriate RTK filter
• Routes through the discover registry (not a hardcoded list), so any tool RTK supports (ruff, mypy, pytest, git, cargo, etc.) is automatically handled
• Supports sequence and cmd task types with recursive resolution
• Falls back to passthrough for unrecognized tools
• poetry run added as a builtin transparent prefix so poetry run poe <task> works end-to-end

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test
• Unit tests for task resolution, command parsing, and filter routing
• Benchmark with real pyproject.toml fixture

[CLAassistant]

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