extract truncation helpers, fix clippy warnings, dedup batching loop

Add util::truncate() and util::first_n_chars() to replace 16 call
sites doing the same floor_char_boundary or chars().take().collect()
patterns. Deduplicate the batching loop in consolidate.rs (4 copies
→ 1 loop over an array). Fix all clippy warnings: redundant closures,
needless borrows, collapsible if, unnecessary cast, manual strip_prefix.

Net: -44 lines across 16 files.

poc-memory/src/neuro/prompts.rs

@@ -118,9 +118,9 @@ fn format_nodes_section(store: &Store, items: &[ReplayItem], graph: &Graph) -> S
         // Content (truncated for large nodes)
         let content = &node.content;
         if content.len() > 1500 {
-            let end = content.floor_char_boundary(1500);
-            out.push_str(&format!("\nContent ({} chars, truncated):\n{}\n[...]\n\n",
-                content.len(), &content[..end]));
+            let truncated = crate::util::truncate(content, 1500, "\n[...]");
+            out.push_str(&format!("\nContent ({} chars, truncated):\n{}\n\n",
+                content.len(), truncated));
         } else {
             out.push_str(&format!("\nContent:\n{}\n\n", content));
         }
@@ -248,12 +248,7 @@ fn format_pairs_section(
         // Node A
         out.push_str(&format!("\n### {} ({})\n", a, ca));
         if let Some(node) = store.nodes.get(a) {
-            let content = if node.content.len() > 500 {
-                let end = node.content.floor_char_boundary(500);
-                format!("{}...", &node.content[..end])
-            } else {
-                node.content.clone()
-            };
+            let content = crate::util::truncate(&node.content, 500, "...");
             out.push_str(&format!("Weight: {:.2}\n{}\n",
                 node.weight, content));
         }
@@ -261,12 +256,7 @@ fn format_pairs_section(
         // Node B
         out.push_str(&format!("\n### {} ({})\n", b, cb));
         if let Some(node) = store.nodes.get(b) {
-            let content = if node.content.len() > 500 {
-                let end = node.content.floor_char_boundary(500);
-                format!("{}...", &node.content[..end])
-            } else {
-                node.content.clone()
-            };
+            let content = crate::util::truncate(&node.content, 500, "...");
             out.push_str(&format!("Weight: {:.2}\n{}\n",
                 node.weight, content));
         }

poc-memory/src/neuro/rewrite.rs

@@ -106,10 +106,11 @@ pub fn differentiate_hub_with_graph(store: &Store, hub_key: &str, graph: &Graph)
 
         // Only propose move if there's a reasonable match
         if best_sim > 0.05 && !best_section.is_empty() {
-            let snippet = neighbor_content.lines()
-                .find(|l| !l.is_empty() && !l.starts_with("<!--") && !l.starts_with("##"))
-                .unwrap_or("")
-                .chars().take(80).collect::<String>();
+            let snippet = crate::util::first_n_chars(
+                neighbor_content.lines()
+                    .find(|l| !l.is_empty() && !l.starts_with("<!--") && !l.starts_with("##"))
+                    .unwrap_or(""),
+                80);
 
             moves.push(LinkMove {
                 neighbor_key: neighbor_key.to_string(),

poc-memory/src/neuro/scoring.rs

@@ -102,7 +102,7 @@ pub fn replay_queue_with_graph(
             let pos = positions.get(key);
             let outlier_score = pos.map(|p| p.outlier_score).unwrap_or(0.0);
             let classification = pos
-                .map(|p| spectral::classify_position(p))
+                .map(spectral::classify_position)
                 .unwrap_or("unknown");
 
             let priority = consolidation_priority(