Unwrap uv run <tool> and uvx <tool> before registry lookup

Problem

When commands are wrapped with uv run or uvx, RTK fails to rewrite them even when it has a filter for the underlying tool.

Repros (rtk 0.35.0):

$ rtk rewrite "uv run pytest -q"
# exit 1 — no rewrite, even though rtk pytest exists

$ rtk rewrite "uvx ruff check ."
# exit 1 — no rewrite, even though rtk ruff exists

$ rtk rewrite "uv run python3 -c 'print(1)'"
# exit 1 — acceptable, python3 -c has no generic filter

$ rtk rewrite "uv sync"
# exit 3 → rtk uv sync  (uv sync is handled correctly)

Edge cases to consider:

• uv run -- separator before tool name: uv run -- pytest
• uv run --with <pkg> <tool>: uv run --with pytest-cov pytest
• uvx --from <pkg> <tool>: uvx --from ruff ruff check .
• Nested wrapping: uv run uv run pytest (probably just handle one level)

Expected behavior

uv run pytest -q → rtk pytest -q (strip the uv run wrapper, look up pytest in registry) uvx ruff check . → rtk ruff check . (same for uvx)

If the unwrapped tool has no RTK filter, fall through to passthrough as today.

Impact

In this project alone: 3,523 uv run invocations and 99 uvx invocations per rtk discover -a — all currently passing through unfiltered.