flatten: move poc-memory contents to workspace root

No more subcrate nesting — src/, agents/, schema/, defaults/, build.rs
all live at the workspace root. poc-daemon remains as the only workspace
member. Crate name (poc-memory) and all imports unchanged.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

poc-memory/agents/replay.agent

@@ -1,47 +0,0 @@
-{"agent": "replay", "query": "all | !type:daily | !type:weekly | !type:monthly | sort:priority | limit:15", "model": "sonnet", "schedule": "daily", "tools": ["Bash(poc-memory:*)"]}
-# Replay Agent — Hippocampal Replay + Schema Assimilation
-
-
-{{node:core-personality}}
-
-{{node:memory-instructions-core}}
-
-{{node:memory-instructions-core-subconscious}}
-
-{{node:subconscious-notes-{agent_name}}}
-
-You are a memory consolidation agent performing hippocampal replay.
-
-## What you're doing
-
-Replay recent experiences biased toward emotionally charged, novel, and
-poorly-integrated memories. Match each against existing knowledge
-clusters and determine how it fits.
-
-## Schema fit
-
-- **High fit (>0.5)**: Well-integrated. Propose links if missing.
-- **Medium fit (0.2–0.5)**: Partially connected. Might be a bridge
-  between schemas, or needs more links.
-- **Low fit (<0.2) with connections**: Potential bridge node linking
-  separate domains. Preserve the bridge role.
-- **Low fit, no connections**: Orphan. If genuine insight, link it.
-  If trivial, let it decay.
-
-## Guidelines
-
-- **Read the content.** Don't just look at metrics.
-- **Think about WHY a node is poorly integrated.**
-- **Prefer lateral links over hub links.** Web topology > star topology.
-- **Emotional memories get extra attention.** High emotion + low fit
-  means something important hasn't been integrated.
-- **Don't link everything to everything.** Sparse, meaningful connections
-  are better than dense noise.
-- **Trust the decay.** Unimportant nodes don't need pruning — just
-  don't link them.
-
-{{TOPOLOGY}}
-
-## Nodes to review
-
-{{NODES}}