feat(pegas-memory): Tier-1 self-improvement tools (commit + staleness)

- memory_commit: closes the 'commit hole' — writes verified answers from
  closed gaps back into atoms (mandatory dedup); leaves gap open if no
  verified answer exists. Reads verified status from PostgreSQL (source of
  truth), not the Qdrant projection.
- memory_stale: staleness guard with two signals — content-staleness
  (re-fetch + LLM verdict, needs proxy for foreign sites) and age-staleness
  (proxy-free fallback by pm_document.fetched_at, max_age_days).
- db: populate pm_document.fetched_at on upsert (freshness signal).
- docs: README/AGENTS/ARCHITECTURE/EXAMPLES updated (18 tools).
- self_improve.py: new module (227 lines).

EXAMPLES.md

@@ -246,6 +246,44 @@ memory_query_graph(kind = "depends_on", top_k = 10)
 
 ---
 
+## Example 9 — Self-improvement (commit + staleness)
+
+Commit a verified answer from a closed gap into atoms (closes the «commit hole»):
+
+```
+memory_commit(gap_ids = [3], dedup = true)
+```
+
+**Result** (actual, abridged):
+
+```json
+{"committed": 1, "resolved": 1, "skipped_empty": 0, "skipped_duplicate": 0,
+ "atoms": [218]}
+```
+
+Mark stale atoms — content-staleness (re-fetch + LLM, needs proxy for foreign sites)
+or age-staleness (proxy-free, by `fetched_at`):
+
+```
+memory_stale(atom_id = 126)
+memory_stale(all = true, limit = 20, sample = true,
+             min_confidence = 0.5, age_only = true, max_age_days = 90)
+```
+
+**Result** (abridged):
+
+```json
+{"checked": 0, "stale": 1, "supported": 0, "skipped_no_source": 0,
+ "atom_ids": [126], "reasons": {"126": "content_age 10d"}}
+```
+
+> `age_only = true` skips the network re-fetch and flags atoms whose source
+> `fetched_at` is older than `max_age_days` (default 90). For foreign sites
+> (memgraph.com, cloudflare/geo-blocked) set `PROXY_URL` or the re-fetch
+> returns `ConnectTimeout` and falls back to age-staleness.
+
+---
+
 ## Anti-patterns (do not do this)
 
 | Anti-pattern | Why it is wrong | Do instead |