tip: unescape bash path backslash escapes (#49691)

[kvnloo]

Tip leaf (fork-only) — CLEAN

Maps to work-order issue #198. Upstream origin anomalyco#49691 (not touched / not promoted).

What: Unescape backslash-escaped chars in bash path args so in-project paths are not treated as external.

Commit: 5029f6d374e767d4fca47f5d7f7e5b34714138fc
Origin tip SHA: 1c0ad219fad94ab01435ab68ad758a804bd9c73b

Proof: fail→pass on packages/opencode/test/tool/shell.test.ts (GREEN 24 / NEG 1 fail / RESTORE 24).

github_writes_origin: 0. Codex promote parked.

[github-actions]

This PR doesn't fully meet our contributing guidelines and PR template.

What needs to be fixed:

• PR description is missing required template sections. Please use the PR template.

Please edit this PR description to address the above within 2 hours, or it will be automatically closed.

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

Hey! Your PR title tip: unescape bash path backslash escapes (#49691) doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.