Split remaining API route modules

[yvette-carlisle]

Summary

• Split search, consolidation, ingestion profile, core memory, sharing, work journal, and admin note handlers into route-owned Rust modules.
• Kept route facade files re-exporting only the handler and OpenAPI path surfaces consumed by route_builder and contract generation.
• Preserved normal Rust module boundaries with explicit crate route visibility.

Validation

• cargo make check after search split: passed
• cargo make check after consolidation split: passed
• cargo make check after ingestion profile split: passed
• cargo make check after core memory split: passed after removing one unused import
• cargo make check after sharing/work journal split: passed
• cargo make check after admin note split: passed

Size

• 24 files changed, 1574 insertions, 1453 deletions