Fix ELP topic selection and replace broken agentic LLM call

elp-input.el: walk frame_nodes to pick the first node whose content
contains the query topic (case-insensitive) rather than always taking
index 0 — prevents the always-high-salience CGI architecture memory
from hijacking every ELP response.

chat.el: rewrite handle_chat_agentic to run the tool loop natively in
El using http_post_with_headers + Map headers, bypassing the broken
llm_call_agentic(model, system, message, tools) C binding that cast a
JSON String as an ElList and never serialized tools. New impl supports
up to 8 tool-use iterations with read_file, write_file, web_get,
search_memory, and run_command dispatch.

elp-input.el

@@ -108,9 +108,24 @@ fn handle_elp_chat(body: String) -> String {
     let frame_nodes: String = if str_eq(kept_json, "") { "[]" } else { "[" + kept_json + "]" }
 
     // ── Reason ───────────────────────────────────────────────────────────────
-    // Extract the patient from the top activated node's content.
-    // Trim to 200 chars so it fits cleanly in a generated sentence.
-    let top_node: String = json_array_get(frame_nodes, 0)
+    // Walk frame_nodes to find the first node whose content contains the topic.
+    // This prevents the always-high-salience CGI architecture node from
+    // dominating every response regardless of what was asked.
+    let fn_total: Int = json_array_len(frame_nodes)
+    let fn_i: Int = 0
+    let topic_lower: String = str_to_lower(topic)
+    let found_node: String = ""
+    while fn_i < fn_total {
+        let candidate: String = json_array_get(frame_nodes, fn_i)
+        let cand_content: String = json_get(candidate, "content")
+        let cand_lower: String = str_to_lower(cand_content)
+        let matches: Bool = str_contains(cand_lower, topic_lower)
+        if matches && str_eq(found_node, "") {
+            let found_node = candidate
+        }
+        let fn_i = fn_i + 1
+    }
+    let top_node: String = if str_eq(found_node, "") { json_array_get(frame_nodes, 0) } else { found_node }
     let top_raw: String = json_get(top_node, "content")
     let patient_raw: String = if str_eq(top_raw, "") { topic } else {
         if str_len(top_raw) > 200 { str_slice(top_raw, 0, 200) } else { top_raw }