Add explicit Bash redirect analysis

[Aaronontheweb]

Summary

• Populate occurrence-level Bash redirect facts for file, descriptor duplicate/close/move, and combined output redirects.
• Preserve arbitrary numeric source descriptors across Bash token boundaries and unquoted continuations; keep overflow, computed, and malformed forms fail-closed.
• Extend executable corpus assertions, live Bash oracles, the canonical grammar, OpenSpec tasks, and implementation plan.

Compatibility and security

• v0.2 compatibility redirects remain populated without reinterpretation.
• Static descriptor operations are explicit non-path facts.
• Computed or unrepresentable descriptors remain incomplete.
• Cwd uncertainty downgrades file redirect and occurrence completeness.
• Bare background-list ampersands remain unsupported.

Validation

• dotnet build -c Release (0 warnings; netstandard2.0 + net8.0)
• dotnet test -c Release --no-build (2313 passed)
• pwsh ./scripts/Add-FileHeaders.ps1 -Verify
• openspec validate v0-3-structured-shell-analysis --strict
• slopwatch analyze --no-baseline --fail-on warning
• Adversarial review GO on frozen diff SHA-256 38472590fd513f590b7ce31be49ea95ca5fd36ef42f05c0fe8e599f3b274a07e