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/transcript.rs

@@ -144,6 +144,35 @@ fn contains_bytes(haystack: &[u8], needle: &[u8]) -> bool {
     haystack.windows(needle.len()).any(|w| w == needle)
 }
 
+/// Get the timestamp of the compaction message at a given byte offset.
+/// Returns a human-readable datetime string, or None if unavailable.
+pub fn compaction_timestamp(path: &str, offset: u64) -> Option<String> {
+    let (mmap, _file) = mmap_transcript(path)?;
+    let start = offset as usize;
+    if start >= mmap.len() { return None; }
+
+    // Find the end of this JSONL line
+    let end = mmap[start..].iter().position(|&b| b == b'\n')
+        .map(|p| start + p)
+        .unwrap_or(mmap.len());
+
+    let obj: Value = serde_json::from_slice(&mmap[start..end]).ok()?;
+
+    // Claude Code transcript entries have a "timestamp" field (ISO 8601)
+    if let Some(ts) = obj.get("timestamp").and_then(|v| v.as_str()) {
+        return Some(ts.to_string());
+    }
+
+    // Fallback: try "createdAt" or similar fields
+    for field in &["createdAt", "created_at", "time"] {
+        if let Some(ts) = obj.get(*field).and_then(|v| v.as_str()) {
+            return Some(ts.to_string());
+        }
+    }
+
+    None
+}
+
 /// Detect whether a compaction has occurred since the last check.
 ///
 /// Compares the current compaction offset against a saved value in