docs(memtrace): fix 4 broken internal links

api-reference/endpoints.md doesn't exist — the actual file is
api-reference/overview.md (with sub-pages memories.md, agents.md,
sessions.md, search.md). use-cases/overview.md doesn't exist either;
the category uses a Docusaurus auto-generated index, so link to the
first concrete page (autonomous-agents.md) instead.

Pre-existing breakage spotted during a link audit; not regressions
from today's multi-tenant doc refresh.

Author: Ignacio Van Droogenbroeck

docs-memtrace/architecture/data-model.md

@@ -306,6 +306,6 @@ ORDER BY importance DESC, time DESC
 
 ## Next Steps
 
-- Explore the [API Reference](../api-reference/endpoints.md) to see how these queries map to REST endpoints
+- Explore the [API Reference](../api-reference/overview.md) to see how these queries map to REST endpoints
 - Read about [Memory Types](./memory-types.md) to understand the semantic model
-- Check out [Use Cases](../use-cases/overview.md) for real-world examples
+- Check out [Use Cases](../use-cases/autonomous-agents.md) for real-world examples

docs-memtrace/architecture/memory-types.md

@@ -190,5 +190,5 @@ Use consistent tags across memory types:
 ## Next Steps
 
 - Learn about the [Data Model](./data-model.md) and storage format
-- Explore the [API Reference](../api-reference/endpoints.md) for memory creation
-- See [Use Cases](../use-cases/overview.md) for real-world examples
+- Explore the [API Reference](../api-reference/overview.md) for memory creation
+- See [Use Cases](../use-cases/autonomous-agents.md) for real-world examples