Delete similarity module, rewrite module, and all text-similarity code

Text cosine similarity was being used as a crutch for operations
the graph structure should handle: interference detection, orphan
linking, triangle closing, hub differentiation. These are all
graph-structural operations that the agents (linker, extractor)
handle with actual semantic understanding.

Removed: similarity.rs (stemming + cosine), rewrite.rs (orphan
linking, triangle closing, hub differentiation), detect_interference,
and all CLI commands and consolidation steps that used them.

-794 lines.

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

src/subconscious/defs.rs

@@ -9,7 +9,6 @@
 //   {{nodes}}     — query results formatted as node sections
 //   {{episodes}}  — alias for {{nodes}}
 //   {{health}}    — graph health report
-//   {{pairs}}     — interference pairs from detect_interference
 //   {{rename}}    — rename candidates
 //   {{split}}     — split detail for the first query result
 //
@@ -227,18 +226,6 @@ fn resolve(
             keys: vec![],
         }),
 
-        "pairs" => {
-            let mut pairs = crate::neuro::detect_interference(store, graph, 0.5);
-            pairs.truncate(count);
-            let pair_keys: Vec<String> = pairs.iter()
-                .flat_map(|(a, b, _)| vec![a.clone(), b.clone()])
-                .collect();
-            Some(Resolved {
-                text: super::prompts::format_pairs_section(&pairs, store, graph),
-                keys: pair_keys,
-            })
-        }
-
         "rename" => {
             if !keys.is_empty() {
                 // --target provided: present those keys as candidates