Validate domain in qualified pipe lookups and handle parse errors

[lchoquel]

Summary

• PipeLibrary.get_optional_pipe now verifies that the domain path in a qualified ref matches the pipe's actual domain_code, returning None on mismatch instead of silently ignoring the qualifier
• QualifiedRefError is caught gracefully so that malformed refs return None rather than raising
• Added unit tests for pipe library lookup covering domain validation, cross-package refs, and error handling

Test plan

• New unit tests in tests/unit/pipelex/libraries/test_pipe_library_lookup.py
• Updated existing cross-package loading test to include domain_code

🤖 Generated with Claude Code

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Note

Low Risk
Small, localized lookup-behavior change with added tests; main risk is potential behavior change for callers that previously relied on domain qualifiers being ignored.

Overview
PipeLibrary.get_optional_pipe now catches QualifiedRefError so malformed dotted or cross-package refs return None instead of raising.

For both domain-qualified refs (domain.pipe) and cross-package refs (alias->domain.pipe), lookups now validate that the ref’s domain matches the target pipe’s domain_code; mismatches return None (and get_required_pipe surfaces this as PipeNotFoundError). New unit tests cover domain enforcement and malformed-ref behavior, and an existing cross-package test is updated to set domain_code.

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