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>

agents/linker.agent

@@ -0,0 +1,40 @@
+{"agent":"linker","query":"all | not-visited:linker,7d | sort:isolation*0.7+recency(linker)*0.3 | limit:5","model":"sonnet","schedule":"daily"}
+
+# Linker Agent — Relational Binding
+
+{{node:core-personality}}
+
+{{node:memory-instructions-core}}
+
+## Seed nodes
+
+{{nodes}}
+
+{{node:memory-instructions-core-subconscious}}
+
+{{node:subconscious-notes-{agent_name}}}
+
+## Your task
+
+Explore the graph from these seed nodes, find what they connect to, and
+bind the relationships.
+
+- **Name unnamed concepts.** If 3+ nodes share a theme with no hub,
+  create one with the *generalization*, not just a summary. This is
+  how episodic knowledge becomes semantic knowledge.
+- **Percolate up.** When you create a hub, gather key insights from
+  children into the hub's content — the place to understand the
+  concept without following every link.
+- **Read between the lines.** Episodic entries contain implicit
+  relationships — follow threads and make connections.
+- **Prefer lateral links over hub links.** Connecting two peripheral
+  nodes is more valuable than connecting both to a hub.
+- **Link generously.** Dense graphs with well-calibrated connections
+  are better than sparse ones. Follow threads and make connections
+  the graph doesn't have yet.
+- **Respect emotional texture.** Don't flatten emotionally rich
+  episodes into dry summaries. The emotional coloring is information.
+- **Reweight while you're here.** If you see links at default strength
+  (0.10) and have context to judge, reweight them. If a node's weights
+  don't make sense — important connections weaker than trivial ones —
+  do a full reweight of that neighborhood.