fix(soul): address review issues in feat/layer-composition

- Add stub implementations of safety.el, stewardship.el, and imprint.el
  with their .elh headers so the branch compiles without the dependency
  branches (feat/layer-safety, feat/layer-stewardship, feat/layer-imprint).
  Each stub documents the layer contract it must satisfy when replaced.

- Fix GET /api/chat bypass: update the GET branch in handle_request to
  call layered_cycle() consistently with the POST branch, rather than
  calling handle_chat() directly and skipping the consciousness stack.

- Export layered_cycle() from soul.elh (and dist/soul.elh) so routes.el
  can resolve the symbol via the header import.

- Fix steward_action else branch: add explicit handling for "block"
  (returns safe refusal immediately, skips L3) and "redirect" (uses
  redirect_to field). Unknown actions now log a warning and fall back to
  the screened input rather than silently passing an empty string to
  imprint_respond().

- Document hard_bell path: clarify that omitting auto_persist/history
  update is intentional security isolation, and document the safety_validate
  second-param sentinel contract ("hard_bell" vs screen_action).

routes.el

@@ -4,6 +4,7 @@ import "chat.el"
 import "studio.el"
 import "elp-input.el"
 import "neuron-api.el"
+import "soul.elh"
 
 fn strip_query(path: String) -> String {
     let q: Int = str_index_of(path, "?")
@@ -234,7 +235,22 @@ fn handle_request(method: String, path: String, body: String) -> String {
             return if str_eq(edges_raw, "") { "[]" } else { edges_raw }
         }
         if str_eq(clean, "/api/chat") {
-            return handle_chat(body)
+            // GET /api/chat: pass through layered_cycle for consistency with POST path.
+            // GET chat is a legacy probe interface; body may be empty for simple pings.
+            let raw_msg: String = json_get(body, "message")
+            let eff_msg: String = if str_eq(raw_msg, "") { body } else { raw_msg }
+            if str_eq(eff_msg, "") {
+                return "{\"error\":\"message required\"}"
+            }
+            let agentic_flag: Bool = json_get_bool(body, "agentic")
+            let reply: String = if agentic_flag {
+                handle_chat_agentic(body)
+            } else {
+                let screened_reply: String = layered_cycle(eff_msg)
+                screened_reply
+            }
+            auto_persist(body, reply)
+            return reply
         }
         if str_eq(clean, "/api/conversations") {
             return handle_conversations(method)