docs: add scoped memory and knowledge bridge RFC

[esafwan]

Summary

Adds a documentation-only RFC for the proposed bridge between HUF conversation data management, scoped memory/data records, Knowledge Sources, Agno-style retrieval architecture, and Hindsight-style long-term memory.

The RFC is intended as a self-contained discussion document for product and engineering refinement.

Why

Current HUF concepts are adjacent but not fully connected:

• conversation-local data management
• Knowledge Sources and Agent Knowledge
• Data Tables
• draft Memory Record storage architecture
• PR docs: RFC for adapting Agno's knowledge/vectordb architecture into HUF #178 Agno-style knowledge/vector architecture
• PR Add Hindsight integration evaluation and recommendation (docs) #225 Hindsight long-term memory evaluation

This document proposes a clean separation:

Conversation Data = temporary working state
Memory/Data Record = canonical scoped learned data
Hindsight-style layer = learning and reflection
Agno-style layer = indexing and retrieval architecture
Knowledge Source = searchable RAG projection
Data Tables = structured business/app records

Key proposal

• Keep conversation data local/default.
• Add a first-class scoped Memory/Data Record layer as canonical storage.
• Add Memory Policy for capture, scope, approval, retrieval, indexing, and expiry.
• Allow selected records to be promoted/projected into Knowledge Sources.
• Treat Agno-style work as the indexing/retrieval half of the bridge.
• Treat Hindsight-style work as the learning/consolidation half of the bridge.

Related PRs

• Builds on discussion from docs: RFC for adapting Agno's knowledge/vectordb architecture into HUF #178 — Agno-style knowledge/vector architecture RFC.
• Builds on discussion from Add Hindsight integration evaluation and recommendation (docs) #225 — Hindsight memory evaluation.

After this PR is opened, #178 and #225 should be updated to reference this bridge RFC as the connecting architecture.

Testing

Documentation-only change.

No runtime code, schema, or frontend files were changed.

[esafwan]

Superseded by the unified implementation in PR #282.

All the code and concepts from this PR have been integrated into that branch, alongside fully functioning background learning agents and hybrid search backends.