Codex: define OCR Lab profile contract for Memory Mesh and Lattice query routing

[mdheller]

@codex Please take this workstream.

Context: Lattice QueryRoutingDryRunPlan now carries lab profile refs under a Slash Topics + New Hope + Memory Mesh governance envelope. OCR Lab should define how document-image extraction profiles are selected without reading local documents in dry-run mode.

Scope:

1. Define an OCR lab profile shape for page segmentation, text extraction, layout metadata, confidence scoring, embedding model selection, retention policy, and evidence refs.
2. Define dry-run profile selection behavior: no document reads, no OCR execution, no remote calls.
3. Map OCR profile outputs into document-query, annotation-query, Memory Mesh, and Sherlock promotion paths.
4. Add fixture/schema validation.

Acceptance criteria:

• Repo-native contract/spec and fixture exist.
• Dry-run semantics are explicit.
• Contract can be referenced by Memory Mesh and Lattice routing without executing OCR runtime.