Support Bazel runfiles dead-code config

[longlho]

Summary

• keep package.json#imports resolution unconditional through the oxc resolver path
• add config aliases that feed oxc resolver aliases and override package imports for Bazel/runfiles escape hatches
• add unresolvedImports modes: report, ignore, and error
• add ignoreUnresolved glob patterns for generated import namespaces such as #virtual_generated/**
• add provider/aspect-backed Bazel fixtures plus codescythe_test targets for runfiles execution and a no-issue false-positive case

Validation

• cargo fmt --check
• cargo test --workspace
• bazel test --test_output=errors //tests/fixtures/runfiles-fixture:codescythe_runfiles_test
• bazel test --test_output=errors //tests/fixtures/runfiles-false-positive:codescythe_false_positive_test
• bazel test //...
• git diff --check