Top Level Memory Definition for pluggable memory in cagent

[venkat1701]

Context

Memory strategies are now represented using named, top-level memory scopes (e.g., a long-term sqlite store) that agents reference explicitly, instead of older/implicit memory configuration patterns. This PR updates the memory demo example and the sqlite memory backend plumbing so the strategy-based configuration works cleanly and consistently, and so CI lint/tests pass.

What I did

Added a new driver-based memory subsystem, implemented the initial sqlite backend, wired memory scopes into team loading/runtime:

Before / After

Before

There was no unified “memory scope” model: team loading couldn’t reliably create per-agent memory tools from named memory configurations, and there wasn’t strategy-aware validation for memory backends/configs.
After

Memory is modeled as named scopes with explicit backends/strategies and validated centrally.
Team loading creates memory drivers once, and agents get memory tools based on their referenced scopes.
The existing memory tool behavior is preserved via an adapter, while enabling future backends/strategies beyond sqlite.

[krissetto]

/review

[github-actions]

Code Review Summary

Reviewed the pluggable memory system implementation. Found 1 high-severity issue that needs addressing.

Issues Found

• HIGH: Resource leak - memory drivers are never closed

Note

The SQL query construction using fmt.Sprintf for LIMIT clause is safe since query.Limit is typed as int, not a string.

The redundant conditional check in validate.go (lines 168-172) is a minor code quality issue but doesn't affect correctness.