Remove memory_research (depended on unreliable SearXNG); research now uses built-in web_search

EXAMPLES.md

@@ -91,9 +91,9 @@ If nothing is found → say "not in the knowledge base" and offer to research it
 1. memory_search("HNSW")            → []                        # not known yet
 2. memory_add_gap("How does HNSW work?",
                   reason = "low_coverage", priority = 0.8)
-3. memory_research("How does HNSW indexing work?")
-                                    → searches the web, ingests sources,
-                                      distills atoms, saves them
+3. web_search(["How does HNSW indexing work?"])   # built-in search
+   web_fetch(chosen_url)              → full page text
+   memory_ingest(url)                 → distills atoms, saves them
 4. memory_verify()                  → cross-confirm the new atoms
 5. memory_search("HNSW")            → now returns verified hits
 ```