ci: narrow Windows test skips

[anp-oai]

Why

The Windows cross-build skip used the broad powershell substring, which hid unrelated Windows tests. Narrowing it exposed the same ConPTY Ctrl-C timeout that is breaking main; that test is not reliable in either cross-built or native Windows Bazel CI yet.

What changed

• scope the cross-build PowerShell carve-out to the dedicated parser-process test module
• exclude the exact ConPTY Ctrl-C test from Bazel CI while leaving local Windows runs enabled
• repeat the exact exclusion in the cross-build config because it replaces the base skip list

Manual validation

• just test-github-scripts
• queried the PTY test target under both ci-windows and ci-windows-cross
• verified the matcher excludes parser-process and ConPTY tests without excluding unrelated PowerShell tests
• Windows shard 4/4 reproduced the main ConPTY timeout before the exact CI-only exclusion was applied

[anp-oai]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: 3582604cc7

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