fix: route wt --version output to stdout

[worktrunk-bot]

Problem

wt --version wrote to stderr instead of stdout, breaking scripts like version=$(wt --version). The reporter hit this while packaging wt as a devcontainer feature and had to work around it with wt --version 2>&1 in a test.

The root cause is in src/help.rs: clap's DisplayVersion error was rendered via eprint\! with the comment "stdout is reserved for data/scripts". But --version output is data that scripts rely on — POSIX convention (and clap's own default when it handles parsing itself) is that --version goes to stdout. Only errors and diagnostics go to stderr.

Solution

Change eprint\! to print\! in the DisplayVersion branch of maybe_handle_help_with_pager, and update the comment to explain the POSIX rationale. No change to DisplayHelp (help text goes through the pager path, which correctly uses stdout when a pager isn't available via show_help_in_pager).

Testing

• Added test_version_goes_to_stdout in tests/integration_tests/help.rs that asserts stdout contains "wt " and stderr is empty. Verified the test fails against the buggy code and passes with the fix.
• Updated the existing test_version snapshot (tests/snapshots/integration__integration_tests__help__version.snap), which had been capturing the buggy behavior (stdout empty, version on stderr).
• Full integration suite: cargo test --test integration — 1416 passed.
• cargo clippy --all-targets -- -D warnings and cargo fmt --check clean.

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Closes #2072 — automated triage