Cross-agent interaction memory lookup

Extend cross-agent memory (Omni/Agent/Memory.hs) to record and index all agent interactions, not just explicit "remember" calls.

Current State

Memory.hs has:

• saveChatHistoryEntry - saves messages with embeddings
• searchChatHistorySemantic - search chat history by similarity
• recallMemories - semantic recall for explicit memories

New Capability

• Record ALL tool calls, reasoning traces, and outcomes across all agents
• Give agents a lookup_past_discussions tool to find:
• "Have we discussed X before?"
• "What did we decide about Y?"
• "What tools did we use for similar problems?"
• Index by: topic embedding, tool names, outcome success/failure
• Cross-agent: coder can find what researcher discovered, telegram bot can reference orchestrator decisions

Design Questions

1. What's the right granularity? Full turns? Tool calls? Summaries? 2. How to handle context limits when injecting recalled context? 3. Privacy boundaries (per-user? per-project? global?)

Related

Builds on existing Memory.hs infrastructure.