Canonicalize recipe input mount paths

[chubes4]

Summary

• Canonicalize recipe input mount targets under /tmp/wp-codebox-inputs before mounting/materialization.
• Preserve original/canonical target metadata on input mounts.
• Rewrite workflow command args with mapped absolute path values using longest-prefix matching.

Testing

• npx tsx tests/mount-materialization.test.ts
• npx tsx tests/staged-input-materialization.test.ts
• npm run test:recipe-runtime-setup-staged-materialization
• npm run build -- --pretty false

AI assistance

• AI assistance: Yes
• Tool(s): openai/gpt-5.5 via OpenCode
• Used for: Implemented the canonical input mount path mapping, workflow arg propagation, focused tests, and verification in collaboration with Chris.