fix: Prevent ConPTY cursor query output (#13077)
## Why
Windows ConPTY sends a cursor-position query during PTY startup. Turbo
answers that internally, but forwarding the query to the user terminal
can make the terminal respond asynchronously and move/corrupt the cursor
while task output is still streaming.
## What
Filter ConPTY cursor-position requests out of Windows PTY task output,
including when the escape sequence is split across reads.
## How
- Added a small Windows-only filter in the PTY output reader.
- Added unit coverage for complete and split cursor-position query
sequences.
- Verified with `cargo test -p turborepo-process child::child_io::tests
-- --nocapture` and `cargo test -p turborepo-process --
--test-threads=1`.
- Pre-push hooks also ran format, TOML check, and Rust checks.
