Native memory tools + MCP server + distill agent improvements

Tools:
- Add native memory_render, memory_write, memory_search,
  memory_links, memory_link_set, memory_link_add, memory_used
  tools to poc-agent (tools/memory.rs)
- Add MCP server (~/bin/memory-mcp.py) exposing same tools
  for Claude Code sessions
- Wire memory tools into poc-agent dispatch and definitions
- poc-memory daemon agents now use memory_* tools instead of
  bash poc-memory commands — no shell quoting issues

Distill agent:
- Rewrite distill.agent prompt: "agent of PoC's subconscious"
  framing, focus on synthesis and creativity over bookkeeping
- Add {{neighborhood}} placeholder: full seed node content +
  all neighbors with content + cross-links between neighbors
- Remove content truncation in prompt builder — agents need
  full content for quality work
- Remove bag-of-words similarity suggestions — agents have
  tools, let them explore the graph themselves
- Add api_reasoning config option (default: "high")
- link-set now deduplicates — collapses duplicate links
- Full tool call args in debug logs (was truncated to 80 chars)

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

poc-memory/src/cli/graph.rs

@@ -186,16 +186,23 @@ pub fn cmd_link_set(source: &str, target: &str, strength: f32) -> Result<(), Str
     let strength = strength.clamp(0.01, 1.0);
 
     let mut found = false;
+    let mut first = true;
     for rel in &mut store.relations {
         if rel.deleted { continue; }
         if (rel.source_key == source && rel.target_key == target)
             || (rel.source_key == target && rel.target_key == source)
         {
-            let old = rel.strength;
-            rel.strength = strength;
-            println!("Set: {} ↔ {} strength {:.2} → {:.2}", source, target, old, strength);
+            if first {
+                let old = rel.strength;
+                rel.strength = strength;
+                println!("Set: {} ↔ {} strength {:.2} → {:.2}", source, target, old, strength);
+                first = false;
+            } else {
+                // Duplicate — mark deleted
+                rel.deleted = true;
+                println!("  (removed duplicate link)");
+            }
             found = true;
-            break;
         }
     }