Move poc-agent into workspace, improve agent prompts

Move poc-agent (substrate-independent AI agent framework) into the
memory workspace as a step toward using its API client for direct
LLM calls instead of shelling out to claude CLI.

Agent prompt improvements:
- distill: rewrite from hub-focused to knowledge-flow-focused.
  Now walks upward from seed nodes to find and refine topic nodes,
  instead of only maintaining high-degree hubs.
- distill: remove "don't touch journal entries" restriction
- memory-instructions-core: add "Make it alive" section — write
  with creativity and emotional texture, not spreadsheet summaries
- memory-instructions-core: add "Show your reasoning" section —
  agents must explain decisions, especially when they do nothing
- linker: already had emotional texture guidance (kept as-is)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/agents/connector.agent

@@ -54,6 +54,27 @@ The test: does this connection change anything? If yes, it's real.
   obvious, it probably already exists in the graph.
 - **Write for someone who knows both domains.** Don't explain basics.
 
+## Setting link strength
+
+Cross-domain connections are rare and valuable — but they vary in
+importance. When you create a link, set its strength relative to the
+node's existing connections.
+
+Link strength measures **importance of the connection**, not similarity.
+Check related neighbors (`poc-memory graph link <node>`) to
+calibrate against existing links.
+
+- **0.6-0.8:** Genuine structural isomorphism or causal link across
+  domains. Changes how you think about both sides.
+- **0.3-0.5:** Productive analogy. Useful for understanding, generates
+  some predictions, but the domains are still mostly independent.
+- **0.1-0.3:** Interesting observation but doesn't change anything yet.
+
+Set with: `poc-memory graph link-set <source> <target> <strength>`
+
+If you see default-strength links (0.10 or 0.30) in the neighborhoods
+you're exploring and you have context to judge them, reweight those too.
+
 {{TOPOLOGY}}
 
 ## Nodes to examine for cross-community connections