Agent identity, parallel scheduling, memory-search fixes, stemmer optimization

- Agent identity injection: prepend core-personality to all agent prompts
  so agents dream as me, not as generic graph workers. Include instructions
  to walk the graph and connect new nodes to core concepts.

- Parallel agent scheduling: sequential within type, parallel across types.
  Different agent types (linker, organize, replay) run concurrently.

- Linker prompt: graph walking instead of keyword search for connections.
  "Explore the local topology and walk the graph until you find the best
  connections."

- memory-search fixes: format_results no longer truncates to 5 results,
  pipeline default raised to 50, returned file cleared on compaction,
  --seen and --seen-full merged, compaction timestamp in --seen output,
  max_entries=3 per prompt for steady memory drip.

- Stemmer optimization: strip_suffix now works in-place on a single String
  buffer instead of allocating 18 new Strings per word. Note for future:
  reversed-suffix trie for O(suffix_len) instead of O(n_rules).

- Transcript: add compaction_timestamp() for --seen display.

- Agent budget configurable (default 4000 from config).

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

poc-memory/src/query/engine.rs

@@ -1314,7 +1314,7 @@ pub fn extract_query_terms(text: &str, max_terms: usize) -> String {
 /// Format search results as text lines (for hook consumption).
 pub fn format_results(results: &[SearchResult]) -> String {
     let mut out = String::new();
-    for (i, r) in results.iter().enumerate().take(5) {
+    for (i, r) in results.iter().enumerate() {
         let marker = if r.is_direct { "→" } else { " " };
         out.push_str(&format!("{}{:2}. [{:.2}/{:.2}] {}",
             marker, i + 1, r.activation, r.activation, r.key));